|Rare Garnets: Tsavorite, Spessartite and Rhodolite
Garnet has historically been highly regarded for its very good hardness (7 to 7.5 on the Mohs scale) and great brilliance. The height of garnet popularity was undoubtedly during 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. While much garnet certainly falls into 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 redder specimens, by iron as well. Found in Nigeria, Mozambique and Namibia, this garnet has been in good supply recently, a situation that experts warn is likely to be temporary. Many different grades of spessartite are currently available, with moderately included material selling for attractive prices. However, 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 1960s 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 specimens are eye clean. Large tsavorites are quite rare; even stones weighing up to two carats are not abundant. Tsavorites range in color from light-green to very dark-green.
Like so many colored gemstones, tsavorite was popularized by Tiffany & Co., who started a special campaign in 1974 to promote it. The promotion only increased the rarity of this already scarce gem. At one time tsavorite was being mined from 40 different areas throughout Tanzania and Kenya. Today there are only four mining ventures that produce commercial quantities.
Rhodolite is a beautiful pink to violet-red garnet. Its name is derived from the Greek word, "rhodon", which means "rose colored". It was assigned its name by George Frederick Kunz after the mountain rhododendron of North Carolina, which has a similar color. By composition, rhodolite falls somewhere between almandine and pyrope. It is not considered a specific garnet subgroup in itself, but describes garnets of the rose or pink rhododendron color. Top quality pink rhodolites are mined in Sri Lanka, Tanzania and Zimbabwe. Large gemstones are rare, but we recently cut some very large rhodolite pieces weighing over 10 carats from some high quality rough 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 uncommon. Another very rare garnet is color change garnet, which is a mixture of spessartite and pyrope garnet. 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.