Dioptase Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Dioptase

Dioptase is abundant in mineral collections throughout the world and is not considered a great rarity, but faceted gems are extremely rare due to a paucity of clean fragments. Clean stones over 1 carat are virtually nonexistent, and few collections have stones at all. Cabochons are blue-green, translucent, and quite attractive but are much too soft for wear.

Dioptase Information

Data Value
Name Dioptase
Colors Rich emerald green, bluish green.
Crystallography Hexagonal. Fine crystals are common in certain localities; stubby, elongated.
Refractive Index 1.644-1.709
Luster Vitreous.
Fracture Luster Greasy.
Hardness 5
Fracture Conchoidal to uneven
Specific Gravity 3.28-3.35
Birefringence 0.053
Cleavage Perfect 1 direction
Dispersion 0.036
Stone Sizes Crystals may be fairly large, but clean areas within such crystals are always very small, and stones are never larger than 1-2 carats. Cabochons up to about 15 carats are sometimes cut from translucent masses.
Luminescence None
Luminescence Present No
Transparency Translucent to transparent.
Absorption Spectrum Broad band at about 5500; strong absorption of blue and violet.
Formula

CuSiO2(OH)2.

Optics

o = 1.644-1.658; = 1.697-1.709. Uniaxial (+).

Optic Sign Uniaxial +

Dioptase Information

Streak: Pale blue-green.

Optics:  o = 1.644-1.658; e= 1.697-1.709. Uniaxial (+).

Occurrence: Oxidized zone of copper deposits. Zaire; Chile; USSR

Arizona: microscopic crystals.

Guchab and Tsumeb, Namibia: world’s finest crystals, some transparent but mostly filled with cleavage planes and fractures. These crystals are a superb color, on matrix, and up to 2 inches long.

Comments: Dioptase is abundant in mineral collections throughout the world and is not considered a great rarity, but faceted gems are extremely rare due to a paucity of clean fragments. Clean stones over 1 carat are virtually nonexistent, and few collections have stones at all. Cabochons are blue-green, translucent, and quite attractive but are much too soft for wear.

Name: From Greek words meaning to see through because the cleavage directions can be determined just by looking into the crystals.