|Rare Garnets: Tsavorite, Spessartite and Rhodolite
Garnet has historically been highly regarded for its very good hardness (7-7.5 on the Mohs scale) and great brilliance. The height of garnet popularity was undoubtedly the 18th and 19th centuries in Europe, where Bohemian garnet jewelry was all the rage.
The popular image of garnet is that of an inexpensive dark red gem, often with a distinct brownish tone. But while much garnet certainly falls in that category, there are some rarer varieties of garnet that have stunning colors and are highly sought after by collectors. These rare varieties of garnet have been responsible for a major resurgence in the garnet market.
Spessartite, the distinctive orange-red garnet, is colored by manganese and, in its redder versions, by iron as well. Found in Nigeria, Mozambique and Namibia, this garnet has been in good supply recently, a situation which experts warn is likely to be temporary. Many different grades of spessartite are currently available, with moderately included material selling for attractive prices. But very clean mandarin orange spessartite is quite valuable, especially in larger sizes.
Tsavorite, a rare grossular garnet, departs even further from the traditional red garnet. Tsavorite is a recent discovery, found for the first time in the 1960's in the border area where Kenya and Tanzania meet. Fine tsavorites are an intense medium green color; a few resemble fine emeralds. Tsavorites may be moderately included; but the finest qualities are eye clean. Large tsavorites are quite rare, even stones up to two carats are not abundant. Tsavorites range in color from a light green to very dark green.
Like so many colored gemstones, tsavorite was popularized by Tiffany, who started a special campaign in 1974 to promote it. But the promotion only increased the rarity of this already rare gem. At one time tsavorite was being mined from 40 different areas throughout Tanzania and Kenya. Today only four mining ventures are still producing commercial quantities.
Rhodolite is a beautiful pink to violet red garnet which was named after the rhododendron flower. Rhodolite falls somewhere in between almandine and pyrope chemically; it is not considered a specific garnet subgroup in itself but denotes garnets of the rhododendron color. Top quality pink rhodolites are mined in Sri Lanka, Tanzania and Zimbabwe. Large sizes are rare, but we recently cut some very large rhodolite pieces over 10 carats from some high quality rough stone from Tanzania.
In addition to spessartite, tsavorite and rhodolite there are a few other rare garnets that we always look for, but rarely find. Demantoid garnet is another green garnet, slightly more yellow/brown than tsavorite, but with a very high refractive index and excellent dispersion. Found only in Russia and Namibia, it is extremely rare. Another very rare garnet is a color change garnet which is a mixture of spessartite and pyrope garnets. It has a dramatic color change from blue to violet that is more intense than the more expensive alexandrite. We occasionally find small lots but they always sell out very quickly.