Tanzanite is often called the "stone of the 20th century", as it was discovered in 1967 and became the first popular natural "substitute" for the blue colour of sapphire. Gübelin & Erni (1999) refer to it as the "blue patrician from Africa" and note: "Of all the novelties that captured people's hearts in the second half of the 20th century, no gemstone was anywhere near as successful as tanzanite."

Many stories are told about the discovery of Tanzanite, including the following:

An Indian tailor named Manuel de Souza had dreamed since childhood of discovering something that would make him a rich man and free of worries. He often wandered through the bush between Arusha and Moshi in northern Tanzania. In July 1967, he was out in the bush strolling around and got lost. He met a group of Maasai herdsmen and sat down by the fire with them. They asked him what he was looking for in the bush and he told them about his dreams. One of the shepherds suddenly pulled a small stone out of his belt and asked Manuel: "Are you looking for something like this?" The stone was deep blue and sparkled in the evening sun, making Manuel's heart beat up to his neck. He thought it must be a sapphire and asked the young shepherd: "Are there sapphires here? Where did you find it?" The shepherd looked at his companions and after a while the leader said: "He is an old man, may the sun of happiness shine on him at the end of his life, lead him there." The two set off an arduous journey with routes often blocked by huge fallen trees, which the Maasai believed had been torn out of the earth by angry gods. They travelled all night, their skin bleeding and torn open by thorns. Mosquitoes stung them and they fell over creepers.

Fortunately, it was worth the effort. With the first rays of the morning sun, they came to a hollow with blue stones scattered on the ground that glittered in the sunlight. "So many sapphires," the tailor thought. Despite his excitement he was realistic enough to take his knife and try to carve one of the blue stones with the sharp point. But behold, the stone could be carved! "So it's not sapphires after all, but what is it then?", he turned to the Maasai. But the Maasai had already disappeared into the bush. As Manuel was familiar with the law, he staked a claim and went immediately to the district capital Moshi to have his claim registered. As the stones were no sapphires, geologists, mineralogists and gemmologists had to prove their identity.

Pic2: View of the tanzanite deposit which is now mined to a depth of over 1000 metres underground (left). The conveyor systems can be seen on the right. Photos: U. Henn, DGemG

At first it was assumed that the stones might be cordierite or dumortierite, but scientific studies at the University of Heidelberg (Bank et al., 1967) determined the material to be zoisite, a collector's stone that had been insignificant until then.

The first specimens were bought by the Tiffany company in New York. Then vice-president H. Platt stated that the stones looked beautiful, but the name was impossible to market them: "Zoisite sounds too much like suicide which prevents superstitious people from buying them." He therefore suggested the name tanzanite which honours the origin – Tanzania is the only country that supplies commercially significant quantities of this blue variety of Zoisite. Within a short time, tanzanite became very popular.

However, the finder of the stones, the tailor Manuel de Souza from Arusha, had talked too much about his discovery and so many gemstone seekers and traders came to the region and did good business with the new stones. He, who should have become a "stone-rich" man, thought they had all stolen from him. His discovery melted between his fingers, and he went back to work on his beautifully ornate old sewing machine. He said: "I found the beautiful blue stones, but they were taken from me; I never took anything from anyone, only from the earth; perhaps the earth spirits were angry with me and punished me for that."

The hallmark of tanzanite is its deep blue colour, which ranges from ultramarine blue to sapphire blue to violet blue. Vanadium is responsible for the colour. Its strong pleochroism is a typical characteristic, i.e. it shows different colours in different directions, namely blue, reddish-violet and yellowish-brown. By heat treatment, the less attractive yellowish-brown hue can be changed into blue in most rough material, thus producing a more attractive colour.

The deposit in the Merelani Hills in northern Tanzania, near Mount Kilimanjaro, is unique. The mine region covers an area of approx. 7 x 1.2 km and is currently being mined to a depth of over 1000 metres underground.

 Pic3: Fine tanzanites with blue (left, approx. 14 ct) and violet (right, approx. 12 ct) body colour. Photos: T. Stephan, DGemG

In 2002, a crystal weighing 3.37 kilograms was discovered and named "Maenzi Tanzanite". An incredible find was made in the mine in 2020 by Saniniu Laizer and his team. He discovered two giant crystals weighing 9.4 and 5.8 kilograms, which he then sold to the Tanzanian government for US$ 3.4 million.

One of the largest cut specimens is the Namunyak Tanzanite (423.56 ct).

Literature
BANK, H., BERDESINSKI, W. & NUBER, B. (1967): Strontiumhaltiger trichroitischer Zoisit in Edelsteinqualität.- Z. Dt. Ges. Edelsteinkunde, Heft 61, 27-29.
GÜBELIN, E. & ERNI, F.-X. (1999): Edelsteine – Symbole der Schönheit und der Macht.- Königsbach-Stein, Verlag Hans Schöner.

Author

Dr. Ulrich Henn, DGemG

© 2023 

Translation

Christine Lucia Matter, DGemG

• Fascination Gemstone
• tanzanite

The name spinel can be traced back to the 16th century. It was mentioned for the first time in 1533 by C. Leonardi, and Georg Agricola (1494-1555) wrote in "De Natura Fossilium": "If carbuncle shows a marvellous red colour and a splendid lustre, it is called spinel". The origin of the name retraces to the Greek spinther = spark, because of the "fiery" red colour, or the Latin spina = thorn, point, which probably refers to the octahedral shape of the crystals. Some spinel octahedrons are so perfect that in Myanmar (Burma) they are said to be "nat thwe", "polished by spirits".

 Spinel octahedron in marble. Photo: DGemG

In the Middle Ages, the term carbunculus (carbuncle) was used for red stones. Albertus Magnus (1193-1280) used the term rubinus for today's ruby, granatus for the red garnet and balagius for the red spinel. The latter led to the term balas ruby, which was used specifically for red spinels from Badakhshan.

Spinel mining in Vietnam. Photo: U. Henn

Ancient Badakhshan, located in what is now the border region between northern Afghanistan and Tajikistan, is the origin of famous red spinels, which were long regarded as "rubies". These include the Samarian Spinel (500 ct, Persian crown jewels), the "Ruby" of Catherine the Great (398.72 ct, Tsar's crown), the "Timur Ruby" (352.50 ct) and the "Black Prince's Ruby" (approx. 140 ct), both part of the British crown jewels, as well as the Catherine Spinel (146.43 ct).

 Selling of rough stones in Vietnam. Photo: U. Henn

The fact that red spinels have been equated with rubies for centuries has several reasons. Firstly, they are very similar in colour, which is also the case with blue spinel and sapphire, and secondly, they are found in the same deposits due to comparable conditions of gemstone formation. In addition, before 1800 it was not possible to differentiate between the two mineral types in terms of crystal chemistry.

Even today, it is the red spinels in particular that are in demand, especially bright red specimens with strong fluorescence, which are marketed primarily in China as "Jedi spinels", in reference to the red laser swords in the Star Wars films. 

Orange Spinel (1.54 ct). Photo: DGemG

The red colour is due to traces of trivalent chromium. Besides Tajikistan (formerly Badakhshan), significant deposits can be found in Myanmar (Burma), Tanzania, Vietnam and Sri Lanka (formerly Ceylon).

In addition to the typical bright red colour, traces of chromium also produce a broad spectrum of pink, orange and purple tones. Chromium together with iron results in mauve or lavender colours, these special spinels come mostly from Sri Lanka or Myanmar (Burma). The red colour shades are known commercially as "crimson", "rose" (pink to pink-orange) and "carmine" or purple-red.

Blue Cobalt Spinel (6.99 ct) Photo: DGemG

Red as most desirable and typical colour is followed by blue. Blue is generally due to iron as a trace element. Especially attractive bright blue colours are produced by divalent cobalt. The origin of such cobalt spinels is Sri Lanka, Vietnam and, more recently, Tanzania. In the trade, the colour of such stones is often called "neon electric blue" or "denim blue".

The demand for spinels, especially bright red and blue coloured stones, has increased in recent years. Eye-clean stones weighing over 10 ct are extremely rare. Spinels are also attracting growing attention at auctions. The famous, bright pink Hope spinel (50.13 ct) achieved a price of £962,500 (€1,125,785) at Bonhams in London in 2015. In 2019, a 17th century necklace with seven red spinels, pearls and an emerald found a new owner at Christie's in New York for over US$3 million.

Authors

Dr. Ulrich Henn und Dr. Tom Stephan, DGemG
© 2022

Translation

Christine Lucia Matter, DGemG

• Fascination Gemstone
• Spinel

Padparadscha is undoubtedly one of the rarest gemstones. The corundum variety, whose most important deposits are the gemstone placers of the island of Sri Lanka (Ceylon), represents a colour interplay of a warm, soft orange with a delicate pink tone. The origin of the name is still the subject of lively debate and no clear classification has yet been found. In Sanskrit, the ancient Indian literary and scholarly language, the name Padmaraja stands for the colour of the lotus blossom. However, the colour of the flower is not orange, but violet, blue, white, red, rose or pink. For centuries, sapphires with a colour consisting of a mixture of pink and orange have been called padmaraga (padma = lotus blossom and râga = colour) by the locals in Ceylon, now Sri Lanka.

Spectacular padparadscha crystal from Sri Lanka. Photo: Company F. A. Becker, Idar-Oberstein.

According to South Asian tradition, this very rare gemstone is “the ruler of the lotus blossom” and had to be given to the king because only he had the right to own them. Hence the name “King Topaz of Ceylon”, which finds mentioning in gemstone books from the first half of the 20th century.

Left: Lotus blossom. Right: Sunset. Photo: U. Henn, DGemG.

The ideal colour of padparadscha is described as a combination of the colour of the Ceylonese lotus blossom (pink) and the sunset (orange). This results in the international description of the colour as “pinkish-orange”. However, in Sri Lanka stones with a stronger pink than orange colour are often referred to as padparadscha as well.

It is important to clearly distinguish this rare colour combination from sapphire varieties that show a pure orange (without pink) or mostly brownish-orange. Such stones originate in most of the cases from deposits in East Africa, namely Tanzania and Malawi, as well as Madagascar. In terms of the causes of colour, orange in corundum is a mixture of red and yellow. The cause of the red colour component is trivalent chromium, while yellow can be caused by defect centres or trivalent iron. Yellow sapphires from Sri Lanka are coloured by defect centres and consequently the orange colour of the padparadscha from these classic deposits is due to an interplay of Cr³⁺ and defect centres. Yellow sapphires from East Africa (Tanzania and Malawi) and most stones from Madagascar owe their yellow colour to trivalent iron. Orange-coloured varieties are therefore caused by a combination of Cr³⁺ and Fe³⁺. Such stones generally do not have an evident pink component but display rather a brownish tint. Such corundums are referred to as orange-coloured sapphires in the trade and are thus distinguished from padparadscha.

The distinction between padparadscha and orange-coloured sapphires is made using absorption spectroscopy in the visual spectral range based on the absence or presence of Fe³⁺ bands in the blue/violet range.

Brownish-orange coloured sapphire from East Africa (0.46 ct). Photo: T. Stephan, DGemG.

A padparadscha of extraordinary size is displayed in the Museum of Natural History in New York. The faceted stone weighs 100.18 ct and originates from Sri Lanka. Exceptional specimens weighing up to over 20 ct have been traded at auctions in recent years and have realised carat prices of over US$ 25,000. In 2005, as an example, an unheated padparadscha of 20.84 ct was sold at Christie's for US$ 374,400 or US$ 17,946/ct and in 2012 an unheated stone of 9.70 ct was sold at Sotheby's in Hong Kong for US$ 250,106 or US$ 25,784/ct.

Authors

Dr. Ulrich Henn & Dr. Tom Stephan, DGemG
© 2022

Literature

Ariyaratna, D. H. (2006): Gems of Sri Lanka.- 6^th ed., Sri Lanka, ScanPlus.

Dharmaratne, P. G. R. (2005): Gem Industry of Sri Lanka.- The Geological Survey and Mines Bureau of Sri Lanka.

Lippelt, U. W. (2001): Padparadscha and/or Padmaraja.- Z. Dt. Gemmol. Ges. 50, 4, 228-230.

Picture of the Lotus blossom: pixabay.com/de/photos/lotus-blume-lotus-bl%c3%a4tter-614421/

• Padparadscha
• History
• Fascination Gemstone
• Curiosities
• Corundum

The use of emeralds for jewellery dates to Egyptian times, when greenish crystals found in the Gebel Sikait area were known as early as 3500 BC. The pits in the area later became known as the “emerald pits of Cleopatra”. The name “emerald” is derived from the ancient Greek word smaragdos, meaning green stone. Emeralds were known in India in 400 BC and the ancient Romans are said to have had knowledge of the deposits in the Austrian Habach Valley.

In 50 AD, Pliny the Elder mentions the so-called “Scythian emerald”, which probably originated from emerald deposits on the Tokovaya River near Ekaterinburg in the Russian Urals. However, the Panjir Valley in present-day Afghanistan is also considered a probable source of historical emeralds in the 3rd century BC. An early description “...nothing is greener than an emerald” goes back to Pliny the Elder.

Typical Colombian emerald specimen: Emerald crystals with small golden pyrite on calcite in a black mudstone.

The most important emerald deposits in the world today are found in Colombia. It is assumed that they were known to the indigenous people living in the region as early as 1000 AD, who worshipped the emeralds as the tears of Princess Fura. However, the economic importance of Colombian emeralds only became apparent in the 16th century when they were discovered by the Spanish. In 1560, a Spanish officer discovered the green crystals by chance when his horse stumbled over a root. The legendary Somondoco mine yielded beautiful emeralds which were delivered to the Spanish court. From there, they were traded on to other European and Asian aristocrats, which is the origin of today's popularity.

The Andean crown made by Spanish goldsmiths in the Andean city of Popayan in 1593, which adorns the head of the city's patron saint and consists of 453 emeralds set in gold, is of great historical significance. At the end of the 18th century, exploitation, degradation, corruption and smuggling led to a decreasing production for the Spanish crown. At some time, mining came to a complete standstill and the jungle overgrew the mines.

Two famous mining areas, Muzo and Chivor, are still legendary today. Chivor was rediscovered in 1911 by the Colombian mining engineer Francisco Restrepo and the gemstone trader Fritz Klein from Idar, while Muzo resumed production in 1947. The emerald mines of Colombia and the people on the hunt for the legendary green stones in the remote, rugged mountain landscape of the Cordilleras, the Esmeralderos, have shaped the history of this green gemstone in a unique way.

Two terms embody the uniqueness of Colombian emeralds. “Gota de Aceite” (oil drop) characterises the best quality of Colombian emeralds with a slightly “oily”, soft, diffuse green colour. It is said that the finest stones come from the “old” Muzo mine - this is what the name “Old Mine” stands for. The unique colour quality of Colombian emeralds comes from their open green colour without greyish hue and almost no blue undertones due to only very low iron contents. Today, the term “Muzo Green” is used as a colour description in the international emerald trade which stands for the finest shades of green, mostly regardless of origin.

In addition to Colombia, Zambia and Brazil are particularly important production countries for emeralds today. Deposits in Afghanistan and Pakistan as well as Madagascar, Tanzania and Ethiopia provide gem-quality material too. As early as 1550, green stones were found in Brazil which were thought to be emeralds because of their colour but were in fact tourmalines. These tourmalines were therefore called “Brazilian emeralds” for centuries. It was not until the 20th century that actual emeralds were found in Brazil. Today, numerous mines in various federal states supply emeralds in different qualities.

Emerald from Zambia in typical “African emerald colour” and visible inclusion pattern.

In Zambia, formerly Northern Rhodesia, emerald finds were known before 1970 but were only sparce and sporadic. In 1972, rich deposits were discovered at the confluence of the Kafubu and Kafue rivers, yielding beautiful stones with a typical blue hue that is known in the trade as the “African emerald colour”. The largest open-cast mine is the Kafubu mine, which is currently the largest emerald mine in the world.

Left: Three-phase inclusions in a Colombian emerald. Right: Slightly streaky, “oily" growth structures (“Gota de Aceite”).

Chromium is responsible for the green colour of emeralds, partly in combination with vanadium. Emeralds from Zambia have deep green colours with a typical blue tone, as already mentioned, which stems from the presence of additional iron. Some Brazilian stones can have similar colour tones too. Inclusions are very common in emeralds and the term “jardin” was created in the trade for the inclusion images, which are reminiscent of gardens. Characteristics are the three-phase inclusions, which are specific to the origin of Colombian emeralds. The so-called trapiche emeralds are a speciality among Colombian emeralds. They are special crystal formations with a star-shaped, six-centred arrangement of inclusions.

Already 2000 years ago, people knew how to improve the visual quality of cracked stones by oiling them. In Colombia, cedarwood oil was traditionally used to make cracks less noticeable and prevent dirt particles from penetrating the open cracks. Today, synthetic resins, sometimes mixed with conventional colourless oils, are used to ensure a permanent and more stable treatment.

Green is the colour of hope and emeralds stand for happiness, honesty and hope. Already the Romans attributed special powers to emeralds. They believed the stone would change colour if one did not tell the truth. Emerald is the birth stone for the month of May.

One particularly famous emerald is the 217.8 carat Mogul Emerald which is richly engraved with floral patterns and prayer texts which puts its owner under the protection of God. There are many famous rough crystals from Colombia, Zambia or Madagascar, weighing up to several kilograms. These emeralds are exhibited in museums or are privately owned. The largest crystal was found in 2009 in a riverbed in Madagascar and weighs 6.8 kg. The largest emerald specimen comes from Brazil. It consists of numerous crystals, weighs 341 kg and was discovered in 2001. The latest discovery of an extraordinary emerald crystal weighing 1.5 kg was made in July 2021 in the Kagem mine in Zambia. It was named Chipembele, which is the local name for a rhinoceros.

Jewellery with emeralds can be found in many royal treasuries, including the Crown Jewels of England and Iran. Ancient, engraved emeralds can be found in the treasures of Indian moguls. The Star of Atocha, a cut Colombian emerald weighing 12.72 ct, became famous a few decades ago. The rough stone, weighing 25.87 ct, was part of the cargo of the Spanish galleon Nuestra Senora de Atocha which sank in a hurricane off Florida on its way to Spain in 1622. The wreck was found in 1985 and the cargo salvaged, it included many rough emeralds from the mines of Colombia.

Trapiche emerald from Colombia.

Probably the most famous piece of emerald jewellery is Elizabeth Taylor's Bulgari brooch which she received as a wedding gift from Richard Burton and wore it at her wedding in 1964. The brooch is set with an approximately 18-carat Colombian emerald surrounded by 12 pear-shape cut diamonds. When the brooch was auctioned with other pieces of her collection at Christie's in 2011, it achieved a price of US$ 6,578,500 and still holds the record for the most expensive piece of emerald jewellery. One of the finest emeralds that was auctioned in recent years is the “Rockefeller Emerald”, a Colombian eye-clean, completely untreated emerald weighing 18.04 ct. It was purchased by the Rockefellers in 1930 in a brooch and later set in a ring. In 2017, it was auctioned at Christie's and realised a sales price of US$ 5.5 million, which corresponds to US$ 300,000 per carat.

Authors

Dr. Ulrich Henn & Dr. Tom Stephan, DGemG
© 2022

• History
• Fascination Gemstone
• Curiosities
• Emerald