Phenakite is very hard and suited for wear in jewelry, but it is colorless and not exciting to look at. Cut gems have little fire but are very bright. Red gems cut from material from the USSR are seldom seen and are very rare. The normal faceted gemstone is in the 1-5 carat range.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Hexagonal. Crystals rhombohedral, prismatic, acicular; also granular, and in fibrous spherulites.|
|Colors||Colorless; also yellow. pink, brown, pinkish red, all due to surface stains; some crystals are colored by impurities.|
|Cleavage||Indistinct, 1 direction. Fracture conchodial. Brittle.|
|Stone Sizes||Crystals up to 5 >< 10 >< 18 cm have been found, though these are usually heavily flawed. The largest known rough was a pebble found in Sri Lanka that weighed 1470 carats and cut a 569 carat clean gem and several smaller stones. The large stone has many needle-like inclusions. Smithsonian Institution (Washington, D.C): 22.2 (colorless, USSR); 21.9 (colorless, Brazil). National Museums of Canada (Ottawa, Ontario): 23.41 (colorless, Brazil). Private Collection: 21.21, 19.17 (colorless. USSR).|
|Luminescence||Pale greenish or blue in UV light, occasionally pale rose. Sometimes fluoresces blue in X-rays|
|Pleochroism||Observed in strongly colored crystals; for example, in a greenish-blue stone: violet-red/intense blue.|
Optics: o= 1.654; e=I 1.670.
Inclusions: Crystals of aikinite; also mica (Brazil).
Occurrence: In granite pegmatites, often in good crystals.
Pala County, California; Colorado (Pike’s Peak area);
New Hampshire; Lords Hill, Maine.
Kragero, Norway; France; Switzerland; Czechoslovakia;
Usugara district, Tanzania; Klein Spitzkopje, Namibia.
Habachtal, Austria: small gemmy colorless or yellowish crystals.
Virginia: crystals up to 2 inches across.
USSR: reddish color.
San Miguel de Paracicaba, Brazil: large colorless crystals, often clean and cuttable.
Comments: Phenakite is very hard and suited for wear in jewelry, but it is colorless and not exciting to look at. Cut gems have little fire but are very bright. Red gems cut from material from the USSR are seldom seen and are very rare. The normal faceted gemstone is in the 1-5 carat range.
Name: From the Greek for deceiver because it was mistaken for quartz.