Ruby - Mozambique - 15081901102007

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10.28ct

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Table of Contents

At a Glance

Introduction to Colored Gemstones 16

Ruby 23

• Trade 25

• Market 25

• Admiration 26

• Zodiac 27

Origin – Montepuez 28

• Mozambique 28

• Discovery 28

• Deposit 31

• Mining 31

• Sociology 31

• Geology and Genetic Aspects 32

• Gemological Properties 33

• Chemical Fingerprinting and Color 36

• Treatments 37

Geographic Origin Determination• 39

Information & Data 48

Inclusions 56

The ICA | GemLab 71

Index 72

Terms and Conditions 73

Bibliography 74

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Report Number:15081901102007

MONOGRAPH
Mozambique Ruby

Pigeon Blood

10.28 cts

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The ICA

The International Colored Gemstone Association
(ICA) is a non-association and the only worldwide body
specifically created to benefit the global colored gem-
stone industry. ICA was founded in 1984 and now compris-
es over 700 gem industry leaders from mine to market,
including miners, gem cutters, suppliers, retailers, trade
associations, gemological laboratory, academia, muse-
ums, and more from 47 countries who are devoted to ad-
vancing and promoting the knowledge and appreciation
of colored gemstones.

ICA’s global network works to develop a common
language for promotion and consistent business stan-
dards necessary to improve international communication
and trade of colored gemstones.

Over the years ICA has provided direct access to
sources for colored gemstones and related information.
There is no other international organization with the same
collective access and knowledge about all levels of the col-
ored gemstone industry.

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Introduction to
Colored Gemstones

Humans have been obsessed with colored gem- Heat and pressure is generated when two or more
stones ever since the dawn of civilization. Poised for a spar- tectonic plates collide, resulting in the melting and re-solid-
kling future, the jewelry industry is expected to reach over ification of rocks. The boundaries in which the plates grind
USD284.5 billion by 2020 (Dauriz, Remy, & Tochtermann, 2014). over one another are known as gem deposits. Some of the
Jewelry are remarkable and what makes them so special is deposits with major concentrations of gemstones are located
not the brand or designer but is in fact the symbolism and in: The Central-South-East Asia, East-Southeast Africa, East-
history that comes with every ravishing gemstone used. Once South America, Western North America.
a crystal is extracted from the Earth, it undergoes skilled cut-
ting and polishing for the gemstones’ full potential to be re- Before the operation of mines, ancient civilizations
vealed. But, it all began with Mother Nature. used gemstones for many purposes. They were utilized in the
construction of buildings, jewelries, pendants, statues and
Once upon a time, Earth’s landmasses were united even in ancient cosmetics (Harrell, n.d.). Ancient Egyptians
as one supercontinent known as Pangea. Over 200-250 mil- used them for decoration on royal clothing while jade was
lion years, Pangea fragmented and drifted apart to form the frequently buried alongside Ancient Chinese Emperors (Tom,
continents as we know it today. The powerful, gradual process 1989). In Medieval European times, powdered gems were sold
of plate tectonics shuffling and colliding with one another was as medicine and typically taken with herbal tea (Krishnamur-
met with volcanic eruptions and earthquakes. Through mil- thy, 1997). Depending on the culture, gemstones were also be-
lions of years, the violent process gave birth to beautiful gem- lieved to have health benefits and healing powers.
stones.

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As time went by, the veneration of gemstones Sri Lanka were brought back to Europe by the Dutch in great
reached the furthest corners of the world. The growing de- quantities (Frangoulis, 2015). Indian diamonds, worn by their
mand for gemstones, advancement of technology and expan- elites spread to the royal courts of Europe who were all afflict-
sion of trade encouraged the permanent operation of mines ed with the diamond craze. The demand from the Europeans
along the gem deposits. Bygone were the days where one over these exotic gemstones were one that traders and mer-
would set up nets to catch gemstones as they rolled down chants alike were glad to fill.
the mountainside during heavy rain or flood. From within the
mines of Ratnapura in Sri Lanka, the province of Kanchanab- Among the long list of over 100 different types of
uri in Thailand, the Mogok Township in Myanmar, all the way gemstones, the following three gemstones are considered the
to the world’s oldest working gem mines Colombia, precious more popular ones: emerald, ruby and sapphire. These three
gemstones scattered around the globe. stones have long been associated with royalty, shedding light
on why they are an object of fascination in our modern-day
We can’t exactly pinpoint the beginnings of the gem society. The first royal to have an enduring affair with Emerald
trade, but what we do know is that the Crusades had much is none other than Ancient Egypt’s Cleopatra. She adored Em-
to do with it. The series of religious wars between Christians eralds so much that she had her own emerald mines (Gempo-
and Muslims opened up the Europeans to the curiosity of ex- ria, n.d.). Faithful servants would work long hours digging deep
otic items from the Middle East and Asia (LeGrand, n.d.). As into the mines to provide Cleopatra with the beautiful green
the Europeans spent more time in the Middle East, they came stones. It would then be used to decorate her robes and royal
to the realization that the Arabs had been trading with places ornaments.
much further east. Crusaders who returned from the Middle
East brought back an assortment of items such as perfumes, Long known to house some of the world’s best ru-
spices, and silk. Among them were gemstones. bies, Siamese ruby is found only in Thailand. Traditionally used
on Buddha images and royal insignia, the Thai royal family has
It wasn’t until the 17th century that the gem trade a long relationship with rubies. The most expensive of all the
started to kick off. The formalization of trade organizations rubies in Thailand is a 21-carat Siamese ruby which sits atop a
such as the Dutch East India Company opened a world of new 180-carat diamond tiara, decorated with an additional 24 piec-
trade routes and communications between the West and the es of the Siamese ruby (Pholdhampalit, 2017). In the Thai cul-
East. Gems such as the brightly-colored tourmalines found in ture, rubies symbolize the sun and therefore it is always placed
at the center of each piece.

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It is almost impossible to speak about royal families and their
jewelry without mentioning the British royal family. Whilst each member
of the family has their own collection of jewelries, the history of the Brit-
ish Empire is intertwined with sapphires, notable for their fondness of the
jaw-dropping stones of blue. For example, two of the world’s most legend-
ary sapphires are found on the Imperial State Crown: the 104-carat Stuart
Sapphire and the rose-cut St. Edward’s Sapphire (Royal Collection Trust,
n.d.). The Queen also boasts an abundance of brooches featuring large
sapphires as the centerpiece.

While the world focuses on rubies, emeralds and sapphires, in-
terest towards other gemstones such as topaz, opal and garnet has been
brewing. The younger generation’s tastes seem to be shifting away from
diamonds towards colored gemstones (Jenkins, 2018).

There is no denying that one glance at these any gemstone can
have such a strong effect on us. It is as if we are staring at a million-year-old
piece of history, molded by the earth and Mother Nature herself, smiting
everyone with its beauty and glorious shine. For these reasons, gemstones
have held so much value throughout mankind’s history. Ancient civiliza-
tions believed them to possess the ability to forgo diseases and illness,
powers of protection from witchcraft and safeguard from evil but today,
the gemstones fetch high soaring prices at auction houses and are still the
decorations on royal adornments.

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Ruby

Rubies have a rich history spanning over 2,500 years capti- Geology
vating everyone who has had the pleasure of encountering it. Even
though they are found in almost all parts of the world, that doesn’t One of the rarest gemstones from the corundum mineral
mean it’s appreciated any less. The stone has had thousands of years of species, rubies are famed for its hardness, durability and rarity. The
exposure to different cultures, highlighting its popularity and creating name comes from the Latin word “ruber” meaning red. Chromium, a
a snowball effect. The luxurious red stones are now the most popular trace element found in ruby is responsible for the variation in the gem-
out of all the colored gemstones. Whether you believe the ruby’s pro- stone’s color. A ruby’s color can range from orange-red to purplish-red.
tective and revitalizing powers or are simply drawn towards its mys- The more chromium, the stronger the redness is. Certain rubies with
tique and beauty, a ruby is a wonderful addition to any jewelry lover’s higher iron content will have a darker color and will be shine less as iron
collection. eliminates the glow. They are typically found in marble, metamorphic
rock and basalt rocks.

Rubies are formed when they are treated to extreme heat
and pressure under earth’s surface. They are typically found in marble,
metamorphic rock and basalt rocks.

An important factor affecting the price of a ruby is its color.
Rubies that glow with a pure, vibrant red to a slightly purplish red color
are the ones people currently desire. Those that are dark and too pur-
plish or orangy will be priced lower. On the other hand, if they are too
light, they will be considered pink sapphires and therefore will also be
priced lower (Gemological Institute of America, n.d.). There needs to be
a perfect balance. Regarding inclusions, the ones that fetch the high-
est prices are free of eye-visible inclusions. Nevertheless, inclusions are
not always a bad thing. Characteristics known as rutile needles or silk
can help differentiate between naturally formed rubies and synthetic

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Trade Market

While rubies entice those all over the world, Asian In our day and age, the ruby is the most popular
civilizations were the ones that treasured rubies the most. stone in the colored gemstone category. We still see rubies
The Mogok Mines in Burma are the world’s premier source gracing collections of the royal and the elite. We have Queen
of the legendary “pigeon blood” – fiery luminescent crimson Elizabeth’s “Burmese Ruby Tiara” whose 96 rubies were a
in hue – since 600 AD. For centuries, the mines were con- wedding gift from the people of Burma. Another example is
trolled by the Shang Dynasty (Gillis, 2018). Early transport Hollywood actress Elizabeth Taylor’s ruby ring set and neck-
and trading records show that rubies travelled from the East lace which sold at the Sotheby’s auction for over 500,000 USD
to the West via the Silk Road around 200 BC carrying with per carat.
it not only its beguiling beauty, but its lore as well. Western The Burmese Pigeon’s Blood ruby is the highest val-
royalties were attracted to the gemstone and used to show ued ruby in the market. They have a fully saturated red color
status and to maybe gain the believed benefits the gem and are uniquely fluorescent at the same time (AJS Gems,
brought to its owner. n.d.). Some stones have silk inclusions within them. One pop-
ular Pigeon’s Blood ruby that topped the lot of jewelry auc-
King Nuha-Thura Maha Dhama-Yaza of Burma an- tioned off at the ‘Jewels For Hope: The Collection of Mrs. Lily
nexed the Mogok regions in 1597 and gained direct access Safra’ event held in 2012 by Christies is the “Hope Ruby”. The
to the ruby deposits (Ali, 2017). The King decreed that rubies ruby was designed by the House of Chaumet, a high-end jew-
of a certain weight or size must be handed over. Miners be- eler based in Paris. Boasting a vivid red, cushion-shaped Bur-
gan to practice breaking larger rubies into smaller pieces to mese Ruby with Mogok characteristics, the Hope Ruby was
avoid surrendering their stones. The practice lasted up until sold for USD 6.7 million (DeMarco, 2012), a world-record price
the 19th century when Great Britain occupied the region. for any ruby sold at auction. In 2015 the world-record title was
For over 300 years, the mines in Mogok were under strict stolen by the “Sunrise Ruby” described as “a unique treasure
control of the Burmese rulers (Ali, 2017). of nature”. With its vivid and saturated red color, it sold for over
USD1 million per carat (USD30.4 million in total) to a private
buyer in Switzerland.

Supply of the rare ruby from Burma is slowly dwin-
dling. As more and more people are in demand of the stone,
African Rubies are stepping up the plate. They are popular for
suiting all tastes because of the large size and abundance of
colors they come in ranging from dark pink to dark red.

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Admiration

Red is the color that best represents our intense emo-
tions: anger, fury, passion, and love. Our blood is also red and an-
cient civilizationts sometimes treasured rubies for holding the
power of life. It is not hard to see why there is such mysticism
surrounding this gem, one look at its color would automatically
evoke thoughts of power and virility, its glow seemingly hold-
ing an inner fire. Quoting the famous American mineralogist
George Frederick Kunz, “The flashing and ruddy light of the
ruby suggested an igneous origin, and induced the belief that
rubies were generated by a fire from heaven, in other words, by
the lightning flash” (Kunz, 1971). The belief was so strong that if
a ruby was cast into water, people were certain the liquid would
boil.
Mystical powers such as protection against negative
energy, vampirism, psychic attack and increasing a person’s
strength were attributed to rubies (Shimmerlings, n.d.). Medic-
inal usages including blood detoxification, prevention against
starvation and protection from the plague all added to rubies
popularity.

Burmese soldiers used to embed rubies into their flesh
before battle to ensure their safety and victory. The Chinese be-
lieved rubies to be a self-illuminating stone and even the Chi-
nese Emperor himself would use a ruby to light his room up.
In the middle ages, rubies were thought to bring good health,
guard against sexual desires and even help resolve disputes.
Abilities of precognition were also linked to rubies as a stone
turning darker would signal the owners misfortune, illness or
death (Hess & Emporia State University, 2003).

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Hinduism has strong relations with the fire-born Zodiac
gemstone (also known as “Ratnaraj” or the ‘King of Pre-
cious Stones’) believed to be one of the fruits of the myth- In the middle ages, twelve gemstones were con-
ical Kalpa Tree. When worshipped to the god Krishna, the nected to the twelve apostles and then they were associ-
reward would be the power of reincarnation – reborn as ated with the twelve months of the calendar. While the or-
a mighty emperor. In Catholicism, rubies are mentioned der of the gems in relation to the apostles have changed
four times in the bible and were said to be God’s most pre- throughout the years, the association of gemstones with
cious gemstone out of the 12 stones he created. It is no specific months have remained intact. Zodiac gemstones
wonder that rubies have managed to retain theirs impor- should also not be confused with birthstones. Zodiac
tance in the Western world, heavily sought-after by Euro- gemstones are astrological and not based on the twelve
pean royalty and the upper class (Gemological Institute of months of the calendar. Regardless, many people believe
America, n.d.). that wearing a gemstone that relates to your astrological
sign or birth month can bring about good luck.

Rubies are the birthstone for those born in July
as well as the gemstone for the astrological sign of Cap-
ricorn. Rubies symbolize love, passion, courage and emo-
tion. Wearing a fine red ruby will bring harmony and good
fortune to the wearer. Owners can expect a peaceful life.

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Origin-Montepuez

Mozambique Natural resources in Mozambique play a large role in
the world’s production of beryllium, tantalum and aluminum
Mozambique is a biodiverse country in the south- (Yager & U.S. Geological Survey, 2006). The mining section also
eastern coast of Africa rich in natural resources. Mozambique accounts for much of Mozambique’s economy, especially the
covers an area of about 799,380 km2 and has a population coal and gas industry. Gas reserves are predicted to be the
of about 27 million people (Central Intelligence Agency, n.d.). fourth largest in the world.
The capital city is Maputo, known for beautiful colonial-era
architecture and picturesque natural settings. The tropical Other mineral deposits include gold, asbestos,
country faces towards the Mozambique Channel which acts graphite, marble, manganese, graphite, platinum, nickel and
as a natural barrier between Madagascar and the African diamonds among the many (Penvenne, & Sheldon, 2013). The
mainland (Penvenne, & Sheldon, 2013). recent discovery of ruby deposits adds on to the extensive list
of Mozambique’s natural resources.
Due to over four centuries of Portuguese rule, the
country’s official language today is Portuguese even though Discovery
most people speak languages from the Bantu branch (Pen-
venne, & Sheldon, 2013). The history of rubies in Mozambique can be traced
back to the colonial era when it was discovered by the Euro-
Mozambique is home to roughly 232 species of peans. There were whispers of Mozambique’s ruby deposits in
mammals and 740 species of birds, some of which are on the gemstone industry, many of which were mined illegally.
the verge of extinction. These animals live in the dense forest
and opens forests scattered around the country (Penvenne, In 2009, a local farmer named Suleimane Hassane
& Sheldon, 2013). To protect the endangered species, there came across the ruby deposits in Montepuez. He stated his
are 13 forest reserves, seven national parks, three conserva- claim over the land but because he was poor and illiterate,
tion areas and three game reserves. he was no match for Gen. Raimundo Pachinuapa, a mem-
ber of the ruling Mozambique Liberation Front (Valoi, 2016).

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Mozambique

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Even though Hassane was the one who discovered the rubies,
Gen. Pachinuapa acquired the rights to the land - something very
common in Mozambique where government officials often exploit
their citizens in ruthless land grabs as claimed by the World Bank
(Valoi, 2016).

Shortly after, Gen. Pachinuapa’s company called Mwiriti
obtained license to explore the ruby deposits and by November
2009, he claimed the rights to over 81,000 acres in the ruby depos-
its. Till this day, Mwiriti maintains their innocence in the illegal ac-
quisition of the lands. Gen. Panichuapa began looking for foreign
partners and in 2011, he struck a deal with a natural resources com-
pany headquartered in London called Gemsfield. Together, they
formed a joint venture under the name Montepuez Ruby Mining
(Valoi, 2016).

Rubies from Mozambique are considered some of the
best to ever come out of Africa, well known for their large size.
There is growing attention in the gemstone market for these rubies
which are popular for suiting all tastes because of the abundance
of colors they come in. Their color ranges from dark pink to dark
red, bridging the gap between the highly fluorescent Burmese Ru-
bies and Thai - Cambodian Rubies which are not fluorescent. What
makes them special is that a great deal of Rubies from Mozam-
bique have a combination of clarity and color that does not require
heat treatment.

When Gemsfield held their first ruby auction in 2014, they
sold 1.82 million carats out of 2.03 million carats and generated
roughly USD33.5 million in revenue over six days (Diamond, 2014).

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Deposit Sociology whole in and around its ruby mine in Mozambique and
emerald vein in Zambia. For every dollar in revenue the
Mozambique Rubies that exhibit the desired Etelvina Rita Ja, the district administrator of London-based company makes, they have vowed to
Pigeon’s Blood red color are mined from the deposits Montepuez stated in 2017 that the strength of a strong spend 32 cents on ethical practices such as sustainable
in Montepuez. It is lauded as the most important ruby ruby market will reflect in the development of the Mon- initiatives, social programs and a 10% increase on the in-
deposit in the 21st century by the Gemological Institute tepuez region and Mozambique as a whole (Boswell, dustry’s minimum wage for their employees. As part of
of America (Valoi, 2016) and is about 33,600 hectares 2017). As the demand for Mozambique Rubies grow, so their mission to transform the communities around the
in size. Many believe that over 40% of the world’s un- does the Mozambique economy. But, we have to bear mines, flourishing vegetable farms have been set up,
mined rubies could be here (Boswell, 2017). in mind that while an increase in supply and demand is operating as a co-op between local families from sev-
good for the country’s economy, it may not be good for en different villages. The produce grown guarantees 5
The Montepuez mines is located in the Mon- the people - especially those working for Gemfields. times the profit for the families which they could sell at
tepuez district of the Mozambican province of Cabo local markets or consume themselves.
Degaldo. Located in the northernmost part of Mozam- Gemfields and the entire mining operation
bique, the Montepuez district has a population of about in Montepuez have been under scrutiny for some time The new program is driven by young luxury
185,00 people and covers an area of 15,871 square me- now. The land was allegedly stolen from the local villag- buyers, particularly from North America, who demand
ters. The ruby deposit itself is situated south of Naman- er who discovered and one could say that the way ev- to know the origins of their stones and whether or not
humbire village, 30 km from Montepuez Town (Mindat, erything was handled was corrupt. Aside from the way they were sourced ethically. These young buyers are
n.d.). the mining operation was started, Gemfields has also tech-savvy millennials capable of digging into a com-
been accused of serious human rights abuses. Just last pany’s ethics and practices and are willing to share crit-
year, a law company brought forward a case with over icisms online in response to any issues that upset them.
Mining 100 community members claiming that many of them We can never be too sure whether the allegations of
suffered human rights abuses at Montepuez. Four human rights abuse are true or not. But, it is always im-
Gemfields utilizes the open-pit mining tech- claimants even alleged that Gemfield security forces portant to be weary and spread the message that a sus-
nique to extract rubies from the earth. Open-pit mines shot and killed their sons (Hill & Nhamire, 2018). The tainable and ethical mine-to-market supply chain must
are used when deposits of rocks or minerals are found mining company defended itself by stating that many be achieved.
near the surface and are excavated from an open pit of the violent acts were in fact instigated by Mozambi-
as opposed to underground tunneling. To evaluate can police. Nevertheless, Gemsfield has created more
the mineral deposits, Gemfields takes large samples in than 1,000 jobs in the area, provides mobile clinics, and
what is known as the bulk sampling process. As of 2016, has built three schools.
the upgraded processing plant operates at a capacity of
150 tonnes per hour (Gemsfield, n.d.). Recently, Gemsfield initiated a new program
that aims to change the mining culture by committing
to ethical practices that benefit the community as a

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Geology and Genetic Aspects

Corundum forms in different types of host rocks, but it is al-
ways associated with rocks depleted in silica and enriched in alumina.
When silica is present, Al is preferentially incorporated into aluminos-
ilicate minerals as feldspars and micas (Giuliani et al. , 2007). The for-
mation of corundum requires a balanced interplay of several chemical
elements. On one hand, the geological environment must provide suf-
ficient amounts of alumina and the coloring elements chromium (for
ruby) and iron/titanium (for sapphire); on the other hand, the host rock
must be impoverished in silica. Besides this, the PT-conditions must be
in favor of the corundum crystallization. Corundum can be hosted by
different rock types: marble, gneiss, mafic and ultramafic rocks, syenite,
desilicated pegmatites, basalt, granitic skarns, etc. (Kievlenko, 2003).

The global distribution of corundum deposits is closely linked
to collision, rift, and subduction geodynamics. Three main periods of
corundum formation are recognized by Giuliani et al. (2007):
[I] the Pan-African orogeny (750-450 Ma)
[II] the Himalayan orogeny (45-5 Ma)
[III] the Cenozoic alkali basalt extrusions (65-1 Ma).

Ruby deposits of commercial interest were formed during
two periods in the Earth’s history:
[I] the Pan-African Orogeny with the main occurrences in East
Africa/Madagascar and in Sri Lanka, and
[II] the Himalayan Orogeny with the deposits of the so-called
“SE Asian Ruby Belt” in Afghanistan, Pakistan, Tajikistan, Nepal, Burma
(Myanmar) and Vietnam.

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The marble-hosted ruby deposits in Central and Eastern Asia ored veins (now mostly weathered to clay). These veins ranged up to 20
occur in metamorphic blocks that were affected by major tectonic cm thick, and probably originally consisted of syenitic (silica deficient)
events during the Cenozoic Indo-Asian collision (Garnier et al. , 2006). pegmatites and aplites. Ruby was seen in these veins and also in the
Most appreciated rubies in the trade are those found in the marble host overlying boulder-rich eluvium.”
rocks in the Mogok Stone Tract in Burma-Myanmar. These are much
younger than their counterparts in East Africa (Mozambique, Kenya, Gemological Properties
Tanzania) and in Madagascar. However, the geological age of a ruby is
not a criterion for its gemological qualities and beauty. These depend Mozambique rubies are found at several locations in the
solely on how favorable the mineralogical-geological conditions were northern part of the country in the provinces Niassa (e.g. M’sawize,
during its growth history. Ruombeze and Ngauma) and Cabo Delgado (Montepuez area). They
are mined in primary and secondary deposits; their host rock is a so-
Rubies are mined in primary and secondary deposits. Primary called amphibolite (dark-colored metamorphic rock that is composed
ruby deposits found in the gemstone belt comprising today’s Eastern mainly of the minerals amphibole and plagioclase feldspar). Most Mo-
Africa, India, Madagascar, and Sri Lanka are linked to the collision pro- zambique rubies are found as tabular hexagonal crystals of variable
cesses between Eastern and Western Gondwana during Pan-African thickness. Also common is rough material showing abrade features
tectono-metamorphic events. Primary ruby sources are also various (probably mined from a detritic or secondary type deposit; Pardieu et
locations in the Mogok Stone Tract Burma (Myanmar). Ruby mining in al. , 2013).
secondary (alluvial and eluvial) deposits takes place mainly in altered
metamorphic host rocks in Burma (Myanmar), Sri Lanka and Madagas-
car, as well as in the basalt-related deposits in the Thai - Cambodian
border region.

The geological situation in the Montepuez area is described
by Snee and Wu on page 151 in the 2010 summer issue of “Gems &
Gemology”. They stated that “…the rubies are hosted by eluvial material
as well as the underlying weathered bedrock. The bedrock consists of
the Montepuez Complex, a Neoproterozoic suite of metamorphosed
sedimentary rocks (amphibolite-grade schists and gneisses) that were
intruded by granite, granodiorite, and tonalite. The eluvium appeared
to lie directly on Montepuez gneisses, which were crosscut by light-col-

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Rubies originating from metamorphic, mafic-ultramafic imposed on the Cr3+ bands (around 390 and 450 nm); well-devel-
host rocks (composed of mostly dark, iron- and magnesium-rich oped Fe3 peaks (maximum at 388 nm) are rare in Mozambique
minerals), like those from Mozambique, Malawi, or from some de- rubies.
posits in Madagascar can – in general – be quite easily separated
by the gemologists from their counterparts grown in marble-type FTIR spectra of Mozambique rubies show a large varia-
host rocks (rubies from Myanmar, Vietnam, Afghanistan, etc.) or tion of features. In unheated stones, different mineral-related ab-
from those found in basalt-related rocks (e.g. in the Thai - Cambo- sorption bands can be observed. These belong mostly to OH-bear-
dian border region). ing minerals and their presence is an indication that the host ruby
was not submitted to a heat treatment procedure. The following
The gemological properties of Mozambique rubies can minerals have been identified: kaolinite, boehmite and diaspore;
be better understood when keeping in mind the nature and com- rarely observed was the 3161 cm-1 series which is also considered as
position of the amphibolite host mineral amphibole (+ mica) and indication for “non heat treatment”. In heat treated Mozambique
that it is a mafic-ultramafic rock type with high contents of iron rubies, the 3309 cm-1 peak is quite common (generally only very
and magnesium). weakly developed); the “3309 cm -1 series” (with additional peaks at
3232 and 3185 cm-1) is rarer.
The color range of Mozambique rubies goes from pink-
ish red to purplish red to red and (rarely) brownish red. The optical Pardieu et al. (2013) give a detailed description of the
data (refractive indices and birefringence) show the standard val- inclusion features observed in rubies mined in different areas in
ues for ruby (RI = 1.762 – 1.778 and 0.010, respectively). northern Mozambique. The most frequently encountered mineral
inclusions observed were amphibole, mica and chalcopyrite crys-
The UV-Vis-NIR absorption spectrum of Mozambique tals associated with needles, platelets, tubes and bands/planes of
rubies display features that are typical for rubies grown in iron- minute particles. Other inclusion minerals described by different
rich, mafic-ultramafic host rocks (e.g. amphibolites) and that fea- researchers are rutile (present as precipitations or exsolved solid in
ture particularly intense Cr3+. The spectrum clearly features the ‘R’ the form of needles, plates, knives and particles or flakes), zircon,
line in the region of 690 nm, the ‘S’ lines near 660 nm, an intense apatite and cyanite. Tiny particles and very short needles are of-
‘U’ band centered near 560 nm, the ‘B’ lines near 470 nm, and an ten arranged in clouds or band-like formations. Besides this, twin
intense ‘Y’ band centered near 400 nm. Fe3+-related features in lamellae and intersection tubules (also described as “boehmite
the UV-blue spectral region are of variable intensity. In general, needles”), together with healed and unhealed tension fissures are
they are only present as weakly developed bands that are super- common features.

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Chemical Fingerprinting and Color

The mineral corundum is an aluminum oxide. When
it is pure, it contains only atoms of the elements aluminum
and oxygen; pure corundum is colorless. The crystal structure
of corundum is relatively simple but – at the same time – very
compact. Only very few “foreign elements” are accepted in the
corundum lattice, these are mainly iron, chromium, titanium,
vanadium, gallium and, more rarely, magnesium and silicon.

Some of these “impurities” can function as chromo-
phores; this means, their presence causes the development of
different body colors in the corundum host (corundum is called
an allochromatic mineral). The most important chromophore is
the element chromium, it is responsible for pink and red colors.
The combination of the elements iron and titanium results in
different hues of blue; when iron is present as Fe2+ and Fe3+
it can cause yellow and green colors. Vanadium may be respon-
sible for the color change phenomenon observed in certain
sapphires.

For gemologists, the discussion of the chemical fin-
gerprinting of rubies / sapphires is normally restricted to the
elements titanium, vanadium, chromium, iron and gallium, be-
cause these are the only ones that are generally detected when
using standard analytical methods (e.g. EDXRF). The chemical
fingerprinting has become a powerful tool in the gem labs that
are dealing with the geographic origin determination of ruby/
sapphire. The nature of the “foreign elements” in a ruby or sap-
phire reflects directly the chemical conditions prevailing in the
mineralogical-geological environment during the formation of
the gemstone.

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The 6.05 ct ruby described in this Monograph comes the translucent milky white to yellow to brown and bluish white
from Northern Mozambique. It was formed in a metamorphic sapphire from Sri Lanka, known as ‘geuda’, could be trans-
geologic environment. The ruby host rocks in this region are formed to a fine transparent blue by atmosphere-controlled
amphibolites; a typical feature of the amphibolite rocks is a high high temperature heating. This discovery was made possible by
iron content. This explains that rubies that crystallize in such a the availability of simple furnaces capable of reaching tempera-
rock have also high iron concentrations. tures in the ≥1500°C range.

The chemical fingerprinting of Mozambique rubies The heating (thermal enhancement) using chemical
from the Niassa and Cabo Frio states is characterized by additives (so-called flux materials or molten salt solvents, e.g.
variable (mostly medium to high) iron contents (typically from borax) will result in some special processes taking place during
ca. 0.4-0.8 wt.% Fe2O3; rarely iron can go down below 0.2 wt.% the heating and subsequent cooling of rubies and (more rarely)
Fe2O3, such stones may display a distinct red luminescence sapphires. At elevated temperatures and by the action of the
when seen in ultra-violet light. The concentration ranges for solvents dissolved nutrient material will regrow on the walls of a
crack. This is the so-called “healing process” which is closing the
other trace elements in the Mozambique rubies are as follows: crack. But an internal scar remains and develops the so-called
“fingerprint inclusions”. This process that is known as “(induced)
TiO2 ca. 0.005 to 0.1 wt. %; V2O3 up to ca. 0.01 wt. %, often too low healing” is a main feature of the borax treatment.
to be detected when using EDXRF; Cr2O3 ca. 0.3 to 0.8 wt. %;
Ga2O3 ca. 0.005 to 0.01 wt. %.

Treatments

The most common treatment procedures applied for
the corundum varieties ruby and sapphire are: heating (thermal
enhancement; with or without chemical additives); diffusion of
chromophores; fracture filling (clarity enhancement); irradia-
tion processes are only rarely used to improve the color of sap-
phires (especially for Padparadscha).

Corundum has been heat treated with moderate
color improvement since antiquity. However, today’s modern
heat-treatment techniques produce dramatic results when
compared with the subtle changes of the past. The historic
turning point was the discovery, apparently in the 1960s, that

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Heating accompanied by the diffusion of trace vanced analytical techniques (e.g. LIBS; L.A-ICP-MS).
elements from external sources into the body of the gem-
stone can produce an artificial color. In this process, atoms Fracture filling (clarity enhancement) involves the in-
move from the faceted outer surfaces of the gemstone troduction of a liquid, semi-liquid, or solid substance into sur-
inward. Diffusion-treated corundum first appeared on the face-reaching fractures to reduce their visibility and thus im-
world market in the late 1970s. The first corundum diffusion prove the apparent clarity of the gem. Suitable materials for
process brought to market produced blue stones. Titanium such an in-filling procedure to make fissures more or less invis-
was diffused into the colorless material that results from ible are, for example, oil, wax, resin, polymer or different glasses.
heat-treating some of the geuda from Sri Lanka. This pro- In these cases, there is no reaction between the (“mechanical-
cess marked a radical departure from all earlier corundum ly”) in-filled materials and the surrounding fissure walls.
heat treatment in that it produced a thin outer layer of sat-
urated blue coloration in otherwise colorless or pale-col- “Lead glass filled rubies” (sometimes also called “lead
ored sapphire by diffusing titanium into the stone from the repaired rubies”) were first described at the beginning of 2004.
outside. As such, it represented the first successful attempt Lead glass treatment of rubies is performed at relative mod-
to add color to sapphire from an external source. erate temperatures (ca. 800-1,000 °C). At these temperatures,
the aspect of rutile and other inclusion minerals is not affect-
Since about 2000, the heat treatment of corun- ed; the inclusion scenario does, in general, not indicate a heat
dum involving lattice diffusion of beryllium (Be) at tem- treatment. There is no dissolution and now re-crystallization
peratures over 1800°C has become a major issue in the of ruby material, and – consequently – no healing of fissures
gem trade. Although initially only orange to orangy pink observed. The lead glass treatment is best described as a me-
(padparadscha-like) sapphires were seen, it is now known chanical in-filling process of open fissures with glass materi-
that a full range of corundum colors, including yellow and al (this means not involving any chemical reactions). Fissures
blue as well as ruby, have been produced or altered by this filled with Pb-glass are often nearly invisible, because the re-
treatment. It also can reduce the amount of blue in dark fractive index of their filling material is very close to that of the
blue sapphires, rendering them a more attractive color surrounding ruby host.
(Emmett et al. 2003). The Be-diffusion process is, without
question, the most broadly applicable artificial coloration
of natural corundum ever achieved. Analyses have indicat-
ed that the beryllium concentration in the diffused region
is extremely low (only about 10 to 35 parts per million atom-
ic-ppma); a secure proof for the presence of Be requires ad-

26

Geographic Origin Determination phic Belt (MMB). This is a geological structure that extends
over a distance of 4000 km from today’s Saudi Arabia to
Geographic origin determination of colored gem- Antarctica. Its development was the result of the collision,
stones is possible because there is a close relationship be- during the Pan-African orogeny, of the east Gondwanaland
tween the genetic environment, especially nature and (India-Antarctic-Australia) and west Gondwanaland (Africa–
mineralogical composition of the host rock, and the miner- South America) during a period ca. 750-450 million years ago.
alogical-gemological properties of the gems that the gemol-
ogist can study in the lab. The geologic event that created the MMB at the
same time also led to the formation of important gem depos-
Rubies, like all colored gemstones, can be charac- its in different countries, e.g., Mozambique, Kenya, Tanzania,
terized by a series of gemological mineralogical criteria. The Madagascar and Sri Lanka. Among the gemstones that are
gemological properties of the rubies directly depend on the found in different parts of the Mozambique Belt are rubies
set-up of the geological-mineralogical environment in which that originate from primary metamorphic deposits located
they were grown. The gemological properties of a ruby always in Malawi, northern Mozambique (Niassa), different regions
reflect the growth conditions that prevailed during the for- in Tanzania (e.g. Winza in the central-western part or Tundu-
mation of the ruby crystals in nature. Rubies are formed in ru-Songea in the southern part) and occurrences in different
nature in many different geological environments involving areas of the island of Madagascar (e.g. Andilamena, Ilaka-
different host rocks and variable pressure-temperature con- ka, Vatomandry). The separation of the “East African rubies”
ditions. Today it is generally accepted that all gem-quality ru- (including Madagascar) from the marble-type rubies of the
bies are of metamorphic origin. There are no “basaltic-mag- “SE-Asian Ruby Belt” and the basalt-related rubies in the Thai/
matic rubies”. Cambodian border region is a relatively easy task in the gem
labs. However, the distinction of rubies found in certain loca-
Gemstones may reveal a tell-tale combination of tions may be quite difficult, especially for rubies originating
characteristics which permit to identify their country of ori- from mafic-ultramafic host rocks (mostly amphibolite), like
gin. These characteristics are directly related to the geology of those in Malawi, Mozambique and certain localities in Mada-
the region where the gemstone was mined. However, the fact gascar.
that gemstones come from different countries do not neces-
sarily mean that they have formed under different geological
conditions.
A good example for such a situation is given by the
gemstones formed in the so-called Mozambique Metamor-

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Wax Paper Insert Front

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Wax Paper Insert Back

30

Mozambique Ruby

Natural Corundum

10.28 CTS

31

A macro image of the original Mozambique ruby rough weighing
19.35 cts from which the ruby was expertly fashioned by master cut-
ters into the superb 10.27 cts Step/Step cut gem that is the subject of

this ICA | GemLab Monograph Report.

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Line drawings that record three aspects of the original outline of the 1
Mozambique ruby rough from which the ruby was expertly fashioned
33
by master cutters.

A macro image of the original Mozambique ruby rough weighing 19.35 cts from which the Ruby was expertly fashioned by
master cutters into the superb 10.27 cts Step/Step cut gem that is the subject of this ICA | GemLab Monograph Report. The
ruby is shown in this image overlaying the rough to indicate graphically the volume of the rough likely lost in its fashioning.

34

from ROUGH to CUT

The story of the Ruby, or indeed any important gem, is in-
complete without some understanding of the passion and skill
sets that were brought to bear when the rough gem material
was first viewed and purchased by the expert trader. In purchas-
ing the rough he had to visualize the final outcome, the style of
the final cut, the potential colour designation revealed, and the
likely final weight, in order to understand the full potential of the
rough. He also needed to be confident in the team around him
and the passion and skill sets of his cutters who would take the
19.35.ct rough, through the pre-form stages and on to the polish-
ers - the true artisans on which the final appearance rests - who
would reveal all that is best in the fine gemstone.

The image to the left only barely encapsulates the story
from the rough to the fashioned Ruby, however, it does record
the shape and size of the original rough relative to the final su-
perb gemstone that is the subject of this ICA | GemLab Mono-
graph Report. It is an honor for the ICA | GemLab team to have
been privileged to handle and record the details of this fine gem.

35

Information and Data Report Number: 15081901102007

Gemological Identification
& Description

Origin Mozambique
Variety Natural ruby
Species Natural Corundum
Comment No indication of heating

Color Vivid Red, This color is commonly known in the trade as “Pigeon Blood”
Shape Octagonal
Weight 10.28 ct.
Cutting Style Step/Step
Dimensions 13.81 x 9.72 x 7.18 (mm)
Refractive Index 1.762 - 1.770

FTIR EDXRF UV / VIS / NIR
Raman LA-ICP-MS Beryllium Test

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