The gemstone known today as zircon has a long history and has been known by many names throughout the ages. The earliest references to the origin of its name can be traced back to the Old Persian word zargun, meaning gold-coloured, and the Arabic word zerquin, meaning vermilion. These terms evolved into the French word jargon (Old French jargonce, jacunce). A synonym is the term “hyacinth”, which in ancient times probably referred to other gemstones. This name originates from the Greek hyacinthos or the Latin hyacinthus, which were actually the names of a blue flower. Therefore, in ancient times, this name probably referred to a blue or purple mineral, presumably sapphire or amethyst. According to Gaius Plinius Secundus (23–79 AD), the hyacinthos was a purple stone associated with the carbunculus and was therefore probably amethyst.

During the Middle Ages, the name “hyacinth” came to be used for a wide range of colours. Albertus Magnus (1193–1280) distinguished between two types: the whitish-yellow hyacinthus aquaticus and the transparent blue hyacinthus saphirinus. During the Renaissance, “hyacinth” was used to refer to colours ranging from yellow to reddish-brown, particularly red. Georgius Agricola (1494–1555), known as the “father of mineralogy”, described the typical colour as “hyacinth red”.

In the 18th century, the names became more differentiated. In 1773, Brückemann noted that jewellers used the term “cerconier” for the white, clear “Oriental hyacinth” for unknown reasons. It was assumed that this name had evolved from a change or variation in the pronunciation of the French term jargon.

The name “zircon” first appeared in 1780 in the catalogue of minerals compiled by the renowned German mineralogist Abraham Gottlob Werner (1749–1817). He used it to describe the colourless variety of hyacinth. He used the traditional name “hyacinth” for reddish-brown stones, and “jargon” for yellowish-brown ones. At that time, the synonymous names “circonius” for zircon and “schargon” or “sargon” for jargon were used.

In 1789, the German chemist Martin Heinrich Klaproth proved the presence of zirconium earth (zirconium oxide) in zircon, thus establishing it as a mineral in its own right. In 1795, Klaproth analysed hyacinth and found that its chemical composition corresponded to that of zircon. Hyacinth was then assigned to zircon in the mineral classification.

A zircon in the host rock. Image width 5 cm. Photo: DGemG

The increasingly widespread use of the name “zircon”' reflects a shift in focus towards the chemical composition of minerals as opposed to their external characteristics, particularly colour, which had been the predominant factor for many centuries. However, the term “hyacinth” has retained its original meaning in some cases to this day. In his 1860 “Handbook of Gemmology”, Karl Emil Kluge used the term “hyacinth” for “precious zircon” (“Oriental zircon”) and also mentioned the name “zirconite” for “common” zircon.

In his 1969 book “Edelsteine und Perlen” (Gemstones and Pearls), Karl Schlossmacher also refers to the brown to reddish-brown zircon from Thailand and Cambodia as “hyacinth”. Similarly, W. F. Eppler still names yellow to reddish-yellow zircon “hyacinth” in his 1973 book “Praktische Gemmologie” (Practical Gemmology).

However, the old names also retained their meanings. In his 1896 book “Edelsteinkunde” (Gemstone Science), Max Bauer mentions jewellers using the terms “cerconier” or “jargon de Ceylon” for pale yellowish to colourless zircon.

Thus, the name evolved from zargun in Persian, to jargon in French, to cerconier, and finally to zircon, with the name “hyacinth” still occasionally used today.

The most important deposits of gem-quality zircon are found in Asia, where specific names have developed in the respective, sometimes historical national languages. In Burma (now Myanmar), the term Gaw-mate or Gaw-meik is used, meaning “strength”. In Sri Lanka (formerly Ceylon), colourless zircons were called “Matara diamonds” in the 18th century, after a city in the south of the island. This name refers to their special properties, which are similar to those of diamonds — namely, their strong brilliance and high dispersion — and has led to confusion over the centuries.

Zircons come in a wide range of colours: colourless to almost colourless, red, brown, reddish-brown, yellow, yellowish-red, green, greenish-grey, brownish-green, yellowish-green, brownish-yellow, orange, orange-brown, blue and green-blue.

Colourless zircons are rarely found in nature, but they can be obtained from brown and reddish-brown stones by heat treatment, a process that has been known for a long time. Blue zircons also owe their bright colour to a heating process, particularly the ones from Cambodia known as Ratanakiri zircons. Another fancy name description occasionally used for blue zircons is “Starlite” (= shooting star).

In addition to deposits in Asia, including Sri Lanka, Myanmar, Thailand and Cambodia, Madagascar, Tanzania and Australia also supply zircons of various colours for jewellery. Zircons from Tanzania, which range in colour from brown and yellow-brown to pink and pink-brown, are also known commercially as “Malaya zircons”.

Interestingly, zircon is the oldest mineral on Earth, with an age of up to 4.276 billion years.

Exceptional zircons in terms of size and quality can be found in famous collections and museums worldwide. Examples include a 23.85-carat blue stone and a 23.07-carat colourless specimen in the Hixon Collection at the Los Angeles County Museum of Natural History, and a 30-carat orange-brown faceted zircon from Tanzania at the Smithsonian Institution in Washington, D.C., USA.

Exquisite zircons and antique jewellery featuring zircon also regularly appear at auctions. Most of these are blue, such as a 57.36-carat stone that fetched US$60,000, or a necklace with blue zircons and diamonds that sold at Christie's for CHF 47,500.

Zircons of other colours have also occasionally fetched high prices, such as a 41.26-carat brownish-orange-yellow stone from Tanzania, which was set in a ring and auctioned for US$72,000.

Authors

Dr. Ulrich Henn & Dr. Tom Stephan, DGemG
© 2025

• Zircon

In addition to the red and orange garnets described in previous blog articles, the green minerals or varieties of this extensive mineral group are particularly important in the gem and jewellery trade.

Specifically, the garnet minerals grossular and andradite, i.e., calcium-aluminium and calcium-iron garnets, respectively, represent three important gemstones: Mali garnet, tsavolite, and demantoid. These are found in very attractive green colours and enjoy great popularity, especially in combination with the pronounced vividness and brilliancy resulting from their high refractive indices.

Mali garnet

A Mali garnet from the collection of DGemG. 6.07 ct, Photo: T. Stephan

A relatively new gemstone of the garnet group was discovered in 1994 in the West African country Mali. These are iron-coloured mixed crystals of grossular and andradite, mostly yellowish-green or greenish-brown in colour. A speciality are the chromium-coloured green grossulars from the Kayes deposits, known commercially as chrome grossular. In terms of colour, they can be very similar to tsavolites from East Africa. The rough crystals from Mali can reach sizes of more than 10 cm, bur are then largely opaque. Large crystals specimens, for example, over 60 cm in size, are noteworthy. Such large crystals are used for engraved objects. Cut transparent stones usually weigh between 1-2 ct; larger stones are often rich in inclusions.

Tsavolite

Tsavolites from the collection of DGemG. 1.53-2.12 ct, Photo: DGemG

The emerald-green variety of grossular was discovered in Tanzania in 1967 by the Scottish geologist Campbell Bridges, who operated a mine near the town of Komolo, which was later taken over by the state. Bridges then systematically continued his sear and discovered in 1970 deposits in Kenya, close to the Tsavo National Park, where he then operated the famous Scorpion Mine until his violent death in a robbery in 2009. Afterwards, the mine was abandoned and reopened in 2015.

As with the blue zoisite, also discovered in Tanzania a few years earlier and subsequently named tanzanite, a name was sought for the newly discovered green garnet. Here too, it was Henry B. Platt of the New York company Tiffany, who, in 1973, suggested the name tsavorite or tsavolite. While in America the name tsavorite was prevailed, after the place of discovery Tsavo and the ending “ite” often used for minerals, the term tsavolite is used in most German-speaking countries, also after the place of discovery Tsavo and the Greek word lithos for stone. Both names are accepted by the CIBJO.

Trivalent vanadium is responsible for the emerald green colour of tsavolites, which distinguishes them grom green, chromium-coloured grossulars (so-called chrome grossulars).

Since their discovery, a few exceptionally large tsavolite crystals have been found in both Tanzania and Kenya. The largest transparent tsavolite rough stone found to date came from the tanzanite mine in the Merelani Hills of Tanzania and weighed 185 g (925 ct). This was cut to produce the world’s largest clean tsavolite to date, weighing 325.13 ct and measuring 42.11x36.46x28.34 mm. The value of the cut stone is estimated at approximately US$ 2 million. A second spectacular cut tsavolite is the 116.76 ct “Lion of Merelani”, which was faceted from a 283 ct rough stone and is housed in the Smithsonian National Museum of Natural History in Washington. The stone was also discovered near Merelani, Tanzania, in 2017.

In general, the tsavolite crystals mined in Tanzania and Kenya are relatively small, and cut stones of more than 2 ct are rare.

Demantoid

A demantoid garnet from the collection of DGemG with spectacular "horse-tail“. 2.82 ct, Photo: T. Stephan

In 1853, children discovered green pebbles in the Bobrovka River in the Urals. Initially, they were thought to be chrysotile, i.e., olivine or peridot, and were called “Ural chrysolite” or “Siberian chrysolite”. Gold and gem prospectors made further discoveries in rivers north and later south of Yekaterinburg, and the primary deposits were finally discovered at the end of the 19^th century.

When cut, the mostly small stones developed a strikingly fiery appearance and, due to their attractive colour, became very popular at the Tsar’s court and in the jewellery stores of Moscow and St. Petersburg, also known as “Bobrowsk Emerald” or “Ural Emerald”.

The actual identity of the stones as garnets was established by the Finnish mineralogist Nils Gustaf Nordenskiöld in 1864. He identified the green crystals as chromium-coloured andradites and suggested the name demantoid, meaning “diamond-like”, based on their exceptionally strong brilliancy and dispersion. The name was officially adopted by the Russion Mineralogical Society in 1871. In 1887, demantoid was introduced as a new gemstone at the Ural Industrial Exhibition in Yekaterinburg.

Demantoid enjoyed particular popularity in Russia between 1875 and 1920. Examples include various pieces of jewellery from the workshop of the famous Russian court jeweller Peter Carl Fabergé. During this period, demantoids were also exported to Europe and America and were incorporated into jewellery by renowned jewellers due to their exceptional attractiveness – emerald green colour, high brilliancy and high dispersion.

After the Russian Revolution, the demantoid market was politically depressed for a long time, making this high-quality gemstone virtually unsuitable for jewellery production due to its limited availability. It wasn’t until the 1990ties, after the dissolution of the Soviet Union and discoveries in other countries, especially in Namibia in 1996, that demantoid began to experience renewed demand.

Demantoid crystals are generally small, and specimens weighing more than 10 ct are very rare. The largest demantoid ever found comes from the Urals and weighs 252.5 ct.

When cut, stones above 1 ct are already very rare and can fetch prices of several thousand euros per carat. A special characteristic of demantoid garnets are the so-called “horse-tail” inclusions, fibrous inclusions that resemble a horse’s tail. The exact origin and composition of these inclusions are still debated. The mineral chrysotile has been described in Russian demantoids, but recent studies show that they could also be hollow channels. The “horse-tails” are often considered a characteristic of Russian origin, but similar inclusions can also be found in demantoid from other occurrences. Many customers prefer a stone with “horse-tails” to one without inclusions, as long as the inclusions do not significantly impair the brilliancy.

Jewellery pieces with exceptional demantoids find their way into auction houses and achieve high sales prices. Examples include a ring from 1895-1900 featuring a 7-carat demantoid and diamonds, which sold for US$ 101,500 ad Christie’s, and a ring featuring a 6.47-carat demantoid and diamonds, which sold for US$ 89,375 at Sotheby’s.

Authors

Dr. Ulrich Henn, Dr. Tom Stephan & Dr. Thomas Lind, DGemG
© 2025

• Demantoid
• History
• Garnet
• Fascination Gemstone
• Mali
• Mali garnet
• Tsavolite
• Tsavorite

The classic garnet is the red garnet, which has been used for jewellery purposes since ancient times (more information…). However, during the 20^th century, several gemstones in the garnet group became popular, including rhodolite and mandarin garnet.

In 1898, the American mineralogist William Earl Hidden and J. H. Pratt discovered bright pinkish-red to pale violet garnets in Macon County, North Carolina, which they named rhodolite, after the Greek rhodon = rose, and lithos = stone. In English, these are sometimes also called “rose garnets”. Like red garnets, they are pyrope-almandine mixed crystals, but their colour has a distinct pink or rose component, and they are highly transparent.

The North Carolina deposits did not yield large quantities of the new garnet, which is why it was long time considered more of a collector’s stone in the jewellery trade. It wasn’t until the second half of the 20^th century, that additional deposits were discovered, that produced garnets of comparable colour and transparency. Since the 1970ties, this has led to a sharp increase in the popularity of rhodolite (fig. 1) in the gem and jewellery trade. Its importance was further boosted by abundant finds in Tanzania (Ladaban and Kangala) and India (Naktamunda/Orissa). Additional deposits are found in Sri Lanka, Brazil, Madagascar, Mozambique and Malawi. The colour palette ranges from pinkish-red through reddish-pink to purple and reddish-violet, all the way to blue-violet. For several years now, Mozambique has also been supplying intensely purple, almost amethyst-coloured rhodolites, which are often referred to in the trade as “royal purple garnets”.

While classic red garnets often appear a bit too dark due to their high colour saturation, rhodolites impress with their high brilliance thanks to their lower colour saturation.

Some of the largest, fine rhodolites come from Tanzania, including faceted stones weighing over 80 carats. Some of the largest star rhodolites also come from Tanzania, some weighing over 15 carats. Exceptional pieces of jewellery with rhodolite have been sold at various auctions, including a diamond ring with rhodolites for US$ 10.000 and a necklace with diamonds and rhodolites for over € 28.000.

Fig. 2 (left): A mandarin garnet crystal in the host rock. Image width approx. 10 cm, Photo: DGemG. Fig. 3 (right): A faceted mandarin garnet from Nigeria. Collection of DGemG, Photo: T. Stephan.

Another speciality is orange spessartine, which has enjoyed great popularity since the discovery of an exceptional deposit in Namibia in 1992. It is known in the gem and jewellery trade as mandarin garnet.

Spessartine is a manganese-rich garnet that owes its name to a deposit in the Spessart Mountains in Germany. Such garnets were discovered there in 1797, but only gained importance among collectors.

Spessartine of gem quality was later discovered from a deposit in the USA, namely in Ramona County. Stones from this deposit exhibited some attractive orange colours, but due to limited production, demand on the international market was limited. Spessartine from other deposits, such as Brazil, exhibits less attractive orange-brown colours.

For these reasons, spessartine was relegated to a niche existence as a gemstone until the end of the 20^th century.

The discoveries in northern Namibia fundamentally changed the situation. Along the Kunene River (Marien river), the border river with Angola, large crystals were found, some of them with an orange colour of extraordinary luminosity. A debate quickly erupted over the naming of these stones in the gem and jewellery industry. Mineralogically, they were known as spessartine, but this name was already being used for the less attractive orange-brown colours. An initial suggestion was “Hollandine”, after the Dutch royal family, but the international consensus was eventually on the term “Mandarin”.

Among the first discoveries is what is probably the largest faceted Namibian mandarin garnet, weighing 55.4 ct. This stone was examined and certified in 1994 in the laboratory of the DSEF German Gem Lab in Idar-Oberstein. However, the deposits in Namibia were largely exhausted by 1998, and continued mining was no longer profitable.

At about the same time (1999), bright orange garnets were discovered in Nigeria, supplying the industry with the now highly sought-after mandarin garnets. In general, faceted bright orange spessartine in good clarity from Namibia or Nigeria weighing over 5 ct are rare, and specimens over 10 ct are extremely rare. An exceptional large faceted mandarin garnet weighing 39.35 ct is housed in the Housten Museum of Natural Sciences.

In 2007, further discoveries were made in East Africa, specifically in the Loliondo region of northern Tanzania, and recently (2023) another deposit was discovered in the Longido region, also in Tanzania.

Faceted stones from Tanzania generally weigh less than 1 ct, although larger stones are occasionally known. Material of lower clarity that can be processed into cabochons is also available in larger sizes.

Large, high-quality mandarin garnets find their way into internationally renowned auction houses and fetch high prices, for example, a 28,24 ct stone that reached US$ 65.000.

A remarkable piece of jewellery is the “Ramona Orange” necklace from the Michael Scott Collection, featuring 165 ct of orange spessartine and 11 ct of diamonds.

Authors

Dr. Ulrich Henn, Dr. Tom Stephan & Dr. Thomas Lind, DGemG
© 2025

• Granat
• Rhodolith
• Mandarin

The classic colour of garnets is red. The oldest finds of garnet jewellery as grave goods date back to the Bronze Age over 5000 years ago.

Garnet jewellery flourished in antiquity. The Greeks called it anthrakas (after anthrak = coal) and the Romans cabunculus (after carbo = coal), because the stones resembled glowing coals in sunlight. Garnet intaglios in Roman gold, bronze, or iron rings are well known and have been found during numerous archaeological excavations of Roman settlements.

The Roman scholar Gaius Plinius Secundus used the term carbunculus generally for transparent red gemstones, which became “carbuncle” in the Middle Ages.

Albertus Magnus (1193-1280) distinguished three types of carbuncle: balagius (red spinel), granatus (red garnet) and rubinus (ruby). Thus, the modern name garnet first appears in the 13^th century in Albertus Magnus’ book on minerals (De Mineralibus). The name garnet is derived from the Latin granum, meaning “grain”.

In the Early Middle Ages, especially during the Merovingian period, and into the Late Middle Ages, garnet played an important role in jewellery. Famous examples include the Crown of Kech (Kertsch) and the eagle brooch of the Lady of Oßmannstedt from the 5^th century.

The heyday of red garnets began in the 17^th century and lasted until the early 20^th century. Numerous garnet vessels, engravings, and jewellery in important European treasuries and collections bear witness to this. A prominent piece of jewellery is the Order of the Golden Fleece in the Green Vault in Dresden from 1794, a Burgundian order of knighthood containing supposedly the largest Bohemian garnets. Typical garnet jewellery dates from the Biedermeier period (1815-1870), the Victorian period (1837-1901), and the Art Nouveau period (1890-1910).

Fig. 2: Brooch with Bohemian garnet (pyropoe). Early 20th century. Collection of Hermann Lind II, Idar-Oberstein, photo by U. Henn.

Mineralogically, the classic red garnets belong to the complete solid solution series pyrope-almandine. The pure end-members pyrope (Mg₃Al₂(SiO₄)₃) and almandine (Fe₃Al₂(SiO₄)₃) are rare, and are not encountered in gem quality. In the gemstone trade, magnesium-rich specimens are referred to as pyrope, and iron-rich ones as almandine.

The magnesium-aluminium garnet pyrope owes its red colour to traces of chromium (“chrome pyrope”) and/or iron. It was named by Werner (1803) from the Greek pyropos, for fire-eyed or fiery. Bohemian pyropes, whose existence was already known in the Middle ages, became world-famous in the 18^th century. Regular mining already took place in the 16^th and 17^th centuries. The centre of processing into typical Bohemian garnet jewellery, which is nowadays largely important for tourism, is the town of Turnov (formerly Turnau), northwest of Prague. The rough crystals are usually small, with a diameter of up to 6 mm. The average size of polished stones is therefore 1 to 5 mm.

Pyropes from the diamond-bearing kimberlites of South Africa were long called “Cape rubies” because of their blood-red colour.

Fig. 3: Almandine in mica shist. Zillertal, Austria. Image width approx. 6 ct, collection of DGemG, photo by T. Stephan, DGemG.

Almandine is an iron-aluminium garnet and owes its name to Agricola (1546) after the town of Alabanda on the Mäander River in Turkey. The deposits in the Zillertal and Ötztal regions of Austria, discovered by a poacher in 1745, are of historical significance. The heyday of Zillertal garnets was the mid-19^th century, when they were processed into traditional garnet jewellery (traditional costume jewellery), which still enjoys regional significance today. Due to heir high iron content, the crystals found in mica shists are very dark and usually appear black, thus opaque. When reduced to smaller dimensions, they acquire transparency and a deep red colour.

India (“Indian garnet”) has been an important supplier of almandine-rich garnets for the jewellery production for centuries. Significant deposits are in the state of Rajasthan, with its capital city of Jaipur. Large star garnets, which can weigh several hundred carats when cut, are found near Hyderabad.

At the beginning of the 20^th century, vibrant red garnets from East Africa, present day Tanzania, first appeared on the market. The darker Madagascar garnets followed a few years later. Other commercially important deposits of red garnets are Thailand and Mozambique.

Garnets can occasionally reach gigantic sizes, but these are not suitable for cutting. The largest garnet ever found comes from Norway. The irregular shaped garnet block has a diameter of 2.3 meters and weighs 37.5 tons. Several large, well-formed garnet crystals are on display in various museums around the world and can reach sizes of up to one meter.

Fig. 4: Faceted almandine, 5.26 ct. Collection of DGemG, photo by T. Stephan, DGemG.

One of the largest processed garnets is an egg creation by Manfred Wild from Kirschweiler, Germany, designed in the style of famous Fabergé works of art. The two halves of this perfectly cut egg are made of red garnet from India, weighing 5.696 ct.

The Medici Collection in Los Angeles, USA, houses a 3.956 ct star garnet, which was listed on the Guinness Book of Records in 2020. The largest known cut almandine to date is a 175 ct cabochon in the Smithsonian Institution in Washinton, USA.

Among those of historical significance are the pigeon-egg-sized pyrope from the treasury of Emperor Rudolf II, mentioned by Boethius de Boodt in his 1609 “Historia gemmarum”, and a chicken-egg-sized pyrope (468,5 ct) in an Order of the Golden Fleece in the Green Vault in Dresden.

Author

Dr. Ulrich Henn, DGemG
© 2024

• History
• Garnet
• Red garnet
• Pyrope
• Almandine
• Bohemian garnet

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