The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Is a Variety of||Almandine-Pyrope|
|Specific Gravity||3.79-3.80 (Tanzania); 3.83-3.89 (Zimbabwe); 3.84-3.89 (North Carolina).|
Rhodolite is intermediate in composition between almandine and pyrope, with a ratio of Al to Fe of 2 to 1 (that is, 2 pyrope + 1 almandine). The distinctiveness of rhodolite is in its color, which is nearly always a purplish red.
The absorption spectrum always shows almandine lines. Inclusions include apatite crystals (North Carolina) and any of the other inclusions found in almandine. The color of a garnet is misleading, and a chemical analysis is required to show whether a garnet is an almandine or pyrope, or a mixed crystal.
N= 1.750-1.760 (Zimbabwe);
1.760-1.761 (North Carolina);
North Carolina: rhododendron red. lilac, pinkish.
Sri Lanka; Madagascar; India; Tanzania; Zimbabwe.
Smithsonian Institution (Washington, D.C): 74.3, 22.1 (Tanzania); 16.5 (North Carolina).
The original locality for rhodolite was Cowee Creek, Macon County, North Carolina. Stones from this locality are usually very small (under 1-2 carats), but new finds in Africa have yielded gems over 75 carats. Material from the North Pare Mountains, Tanzania, may show a color change, blue in daylight to purplish red in incandescent light, similar to alexandrite (N= 1.765, S.G. = 3.88).
Some say the name rhodolite comes from the Greek word, rhodon, meaning rose. Other scholars compare the name to rhododendron. In either case, the name is comparing the color to a flower.