"Everyone knows about precious diamonds, rubies or emeralds. But only the real experts know about tsavorite. Tsavorite is also called green grossular garnet. It is a rare gemstone mined in the Kenyan part of the Mozambique belt which is in the bushland along the frontier between Kenya and Tanzania in the Tzavo National park.  The sparse mines there are situated in a uniquely beautiful landscape of dry grassland with bare and dry hills. It is a dangerous region, where snakes feel at home and now and then a lion will hunt for prey.

The Brilliant green Tsavorite is rather a young gemstone with a truly ancient geological history.  In 1967, the British geologist Campbell R. Brides was prospecting for gemstones in the north-eastern part of Tanzania. Suddenly he came across some very odd, potato-shaped stone objects. And like in a fairy tale, he found breathtakingly beautiful green grains and crystal pieces inside these weird objects. Gemological tests showed that he had discovered green grossularite, a mineral which had up to then been considered very rare, which belongs to the colorful Garnet family. The stones were very beautiful and of high transparency, so that his find made experts sit up ad take notice. Even Tiffany & Co. in New York expressed their interest in the newly discovered green jewel. But in spite of all efforts it was impossible in those days to get an export license for taking these stones out of Tanzania. Campbell Bridges, however, did not admit defeat. As geologist he knew that those layers in the soil which carry gemstones are generally not limited to just one spot, but usually stretch out over vast areas – and such a layer was what he had encountered according to his opinion. After all, the stone belt which accommodates most of East Africa’s gemstone mines is truly ancient.

Campbell R. Bridges stubbornly continued his search. His theory that the gemstone loaded vein might even extend into the Kenyan territory finally set him on the right track. In the year 1971 he discovered the brilliantly green gemstone for a second time, this time in Kenya, where he could officially register his find and could start exploiting the occurrence. This was the beginning of a new adventure: in order to protect himself from wild animals Bridges lived in a tree house at first. And as he did not want his treasure to be stolen, he cunningly employed the workers’ fear of snakes and had the rough stones guarded by a python snake. It was a beautiful find indeed. Unfortunately, however, the stone was only known to experts. This changed quickly when in 1974 Tiffany’s started a special promotion campaign making Tzavorite well-known in all the USA in only a short time. Other promotion campaigns in other countries followed, and soon Tzavorite was a name known everywhere.

Africa was covered by the ocean millions of years ago at a time when the continents where moving around a great deal more than they are now.  Layers of organic sediment were deposited, and compacted to form shale. The land was subjected to intense heat, pressure, folding and uplift, metamorphically changing the ocean floor into new minerals. This twisting and torturing of the rocks gave birth to the unusual gemstones of East Africa, many colored by the vanadium which is plentiful in these rocks.

Most deposits of tsavorite are found in small and unpredictable pockets.  From a mining standpoint, it is very difficult to figure where to mine next. There have been about 40-50 different areas where tsavorite has been mined. Today, only four mining ventures are still producing. The Scorpion Mine owned by Campbell Bridges is located in Mindi-Kandashi, southeast Kenya. The Aqua Mines, with 3000 acres are located in the Tsavo National Park near Kasigau,  Lualenyi Mine is located in Voi, Kenya and a new tsavorite-producing area was recently discovered in Lokirima, about a thousand kilometers northwest of the previously known localities. Hopes are high that this location will start producing rough suitable for faceting.

Tsavorite is often found in pods which miners call potatoes. The green color is most often due to vanadium or chromium. The early geology which formed tsavorite shattered most of the crystals. Tsavorite mining requires expensive earth removal equipment. It is very rare to find tsavorite in sizes larger than three carats. Most tsavorites are carat size or smaller. (Ed. note: The largest tsavorite we have ever bought/sold was a gem 15.41). Compare this to the wide availability of tanzanite above 10 carats.

Tsavorite has a vivid green color with a high refractive index and double the dispersion of emeralds, giving tsavorite potential greater brilliance. It has a garnet's durability and high clarity.  Tsavorite is often found in pods with a coating of quartz or scapolite, which the miners call "Potatoes". The green color is due to the vanadium from the host rock, but some tsavorite is also colored by chromium. It is very rare to find tsavorite bigger than 5 carats because the heat and pressure which formed tsavorite millions of years ago shattered most of the crystals. 85% of the mined stones are smaller than 1 carat, 10% are bigger than 1 carat, 2.5% are bigger than 2 carats, 1% is bigger than 3 carats.  Only occasionally a rough crystal of over 5 carats is found, so that cut Tzavorites are quite rare and valuable starting from sizes of 2 carats on. The brilliance and luminosity of the stone are displayed even in smaller sizes.

What makes Tzavorite so desirable? First of all there is its vividly brilliant green. The color scale shown by Tzavorite ranges from spring-like pale green via intensely bluish green to deep forest green; colors which have an invigorating and fresh effect on the senses. The gemstone is also coveted because of its high brilliance. Like all other Garnets it enjoys an especially high light refraction index (1.734/ 44).  Compare a tsavorite with an emerald. Both gems were formed under conditions of great stress, and are seldom found in sizes large enough to cut clean stones above two carats. Tsavorite is 200x rarer than emerald, sells for about 1/4 the price, is more brilliant due to a higher refractive index (1.74 vs. 1.596 for an emerald) and is harder than an emerald. Finally, 99.9% of all emeralds are oiled or opticoned and tsavorite is not treated in any way. Tsavorites are more durable, cost less and are more brilliant than emeralds!  Sparks one’s interest doesn’t it!

Campbell and Judith Bridges, Tsavorite USA, Inc.

Contrary to other gemstones, Tzavorites are not heated or oiled. This is not necessary for this gemstone. Like all other Garnets it is a piece of immaculate and pure nature. Another positive characteristic is its robustness. Although showing a hardness similar to Emerald - about 7 1/2 on the Mohs Scale – it is far less sensitive in its handling. This is not only important for cutting and setting the stone, but also for wearing. Tzavorite is less likely to become damaged or to splinter even as consequence of abrupt or incautious impact. It is excellently suited for the favored style of "invisible setting", where stones are set closely joined, and which cannot be recommended for Emeralds. Due to its high brilliance, Tzavorite here is an equal match for the classical stones like Diamond, Ruby and Sapphire.

When collecting cut tsavorite, you need to look for an intense vibrant green color. It should be similar to imperial jade or emerald green. They should be at least one carat in size and a standard shape. You want to avoid gems that look like peridot (green/yellow) or stones that are too dark in tone (green/black). Like emeralds, tsavorite can be green/blue or green/yellow. And like emerald, different collectors have opposing secondary color preferences. There is no market preference on which color is the optimum. In AGL terms, it is practically impossible to receive a straight 3.5 color in emerald; it is similarly as difficult to receive a 3.5 tsavorite. A 4 or 4.5 color tsavorite is a top gem. Tone should be between 65-85. Average brilliancy should be 50% or greater. Proportions and finish should be good (6) or better. You do not want 5.5 colors or 90 tone gems.

Over the past 25 years, Campbell and Judith Bridges have been promoting and marketing Tsavorite worldwide. Mr. Bridges has written many articles for trade and commercial magazines, such as JQ, JCK, Colored Stone Magazine, Msafiri Magazine, & Vogue. He was a speaker at the GIA International Symposiums in 1981 and 1991, lectured at the Tucson Gem and Mineral Show in 1981, The Precious Stones Congress in Tel Aviv in 1983, chaired a panel and gave a presentation speech at the International Colored Gemstone Association Congress in Bangkok in 1987 and was the Kenyan guide and advisor to National Geographic's correspondent in 1991 for a gem article.

The Gem Forecaster” webpage:  www.preciousgemstones.com/gffall96one.html

International Colored Gemstone Association web site: www.gemstone.org/gem-by-gem/english/tsavorite.html

Africa's Secret Treasures, Tsavorite From Kenya: http://www.preciousgemstones.com/gfspr02.html#port