Phenakite Value, Price, and Jewelry Information


faceted phenakite - Russia
“Phenakite,” 12.69 cts, Takowaja River Area, Ural Mountains, Russia. © Rob Lavinsky, www.iRocks.com. Used with permission.

Rare phenakite is a very hard gem material suitable for jewelry. Usually colorless, cut stones have little fire but can be very bright.

Phenakite Value

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Phenakite Value via Gem Price Guide
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Phenakite Information

DataValue
NamePhenakite
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.
Luster Vitreous.
Fracture Conchodial. Brittle.
Hardness 7.5-8.
Specific Gravity 2.93-3.00.
Birefringence 0.016.
Cleavage Indistinct, 1 direction.
Dispersion 0.005.
Luminescence Pale greenish or blue in UV light, occasionally pale rose. Sometimes fluoresces blue in X-rays.
Spectral Not diagnostic.
Transparency Transparent.
Phenomena Chatoyancy.
FormulaBe2SiO4.
Pleochroism Observed in strongly colored crystals; for example, in a greenish-blue stone: violet-red/intense blue.
Optics o = 1.654; e = 1.670. Uniaxial (+).
EtymologyFrom the Greek phenakos for “deceiver,” because this gem was mistaken for quartz.
OccurrenceIn granite pegmatites, often in good crystals. Also, schist-hosted deposits of emerald and alexandrite.
Inclusions Crystals of aikinite; also mica (Brazil). Fine, needle-like tubes can cause cat's eye stones in rare cases.
phenakite rough and cut set - Colorado
Phenakite: Colorado (stone ~2.5). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Comments

Phenakites can show pale yellow, pink, and brown colors, as well as no color. (You’ll seldom see very rare red gems cut from Russian material). With little dispersion, these gems hadn’t generated much excitement beyond collectors of unusual minerals. However, the surge of New Age interest in crystals in the 1990s caught up with this stone. With or without mystical auras, exceptional hardness (7.5 – 8) and indistinct cleavage make this a good, if unusual, jewelry stone.

Recently, gemological laboratories have confirmed cat’s eye gems cabbed from phenakites from Madagascar and Sri Lanka.

This gem belongs to the phenakite mineral group as the beryllium analogue. This very rare element occurs in emerald and alexandrite, too. The gem willemite is the zinc analogue.

phenakite - rough and finished
This phenakite rough, 127 cts, from Nigeria (top) yielded this beautiful finished gem, 35.95 cts, 21 mm. © Dan Stair Custom Gemstones. Used with permission.

Synthetics

Labs have synthesized this mineral, starting with a seed of willemite, no less. However, you’re more likely to encounter quartz gems either erroneously or deliberately presented as phenakites. As rough, this mineral can live up to its etymology. In at least one case, near-colorless phenakite rough was submitted for gemological analysis as suspected diamond. Despite outward similarities, including trigon-like features, these gems have very different optical and physical properties. For example, phenakite has birefringence and a lower specific gravity than diamond.

When found in emeralds as inclusions, phenakites themselves commonly indicate synthetic origins.

Radiation treatments can turn colorless phenakites yellow-brown.

phenakite crystal - Brazil
“If you didn’t know it was a phenakite,” quips Rob Lavinsky, “you would swear it was a killer Herkimer Diamond.” Indeed, this observation points to two possible misidentifications for these gems. People have confused phenakites with both quartz and diamond gems. (So-called “Herkimer Diamonds” are actually double-terminated, water-clear quartz stones). “Phenakite,” Sao Miguel de Piracicaba, Belo Horizonte, Minas Gerais, Brazil. © Rob Lavinsky, www.iRocks.com. Used with permission.

Sources

Gem-quality sources include:

  • United States: Pala County, California; Colorado (Pike’s Peak area); Lords Hill, Maine; New Hampshire; Virginia (crystals up to 2 inches across).
  • Habachtal, Austria: small gemmy colorless or yellowish crystals.
  • San Miguel de Paracicaba, Brazil: large colorless crystals, often clean and cuttable.
  • Russia: reddish color gems.
  • Czech Republic; France; Madagascar; Myanmar; Klein Spitzkopje, Namibia; Nigeria; Kragero, Norway; Slovakia; Sri Lanka; Switzerland; Usugara district, Tanzania.
phenakite - Nigeria
This specimen’s combination of brightness and colorlessness results in a beautiful crystal that’s hard to photograph. “Phenakite,” Jos, Plateau State, Nigeria. © Rob Lavinsky, www.iRocks.com. Used with permission.

Stone Sizes

Faceted gemstones normally range between 1 and 5 carats in size.

Crystals up to 5 x 10 x 18 cm have been found, although usually heavily flawed. The largest known rough was a pebble found in Sri Lanka. Weighing in at 1,470 carats, it cut a 569 carat clean gem and several smaller stones. The large stone has many needle-like inclusions.

  • Smithsonian Institution (Washington, DC): 22.2 (colorless, Russia); 21.9 (colorless, Brazil).
  • National Museums of Canada (Ottawa, Ontario): 23.41 (colorless, Brazil).
  • Private Collection: 21.21, 19.17 (colorless, Russia).

Care

These gems require no special care. See our Gemstone Jewelry Cleaning Guide for care recommendations.

Here’s a video showing a full view of that finished 35.95-ct phenakite. Video © Dan Stair Custom Gemstones. Used with permission.