Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

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Chrysoberyl

April, 2000

Chrysoberyl has suffered a lack of recognition for its own merits, as its two famous siblings get all the attention. Alexandrite, which is color change chrysoberyl and the phenonmenal cat'seye chrysoberyl, are justly appreciated for their rarity and beauty, and I'll feature them in the future essays. Chrysoberyl comes in a range of colors from pure yellow through shades of yellow green to green to brownish yellow to brown. It is a superior jewelry stone. Its hardness at 8.5 (nearly equal to corundum), and its high refractive index and polish luster make a well cut specimen nearly the equal of a diamond in brilliance. Unlike diamond, it is very tough with no cleavages to worry about. The Spaniards and Portuguese of past centuries, were big appreciators of this stone and many historical jewelry pieces with this gem have been found in shipwrecks or can be seen in museum collections. Major sources are Russia, Sir Lanka, Brazil and Madagascar. As the demand is small, there is no vigorous mining taking place, but good reserves of the gem are available should it increase in popularity.

Value

Clean, saturated, yellow and yellow-green stones in larger sizes are most highly prized. Yellow brown and brownish pieces have lower value. Custom cuts add substantial value as the vast majority of chrysoberyl gems in the marketplace are native cut.

Gemological Data:

Makeup: Beryllium aluminum oxide

Luster: Vitreous to subadamantine

Hardness: 8.5

Crystal structure: Orthorhombic

Fracture: splintery to granular

Cleavage: none

Density: 3.71

RI: 1.74-1.75

Birefringence: .009

Pleochroism: weak to moderate, different shades of body color

Dispersion: .015

Stones Currently Available:

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