A Treatise on Diamonds, and Precious Stones/Chapter 2/Section 2
SECT. II.
Chrysoberyl or Oriental Chrysolite[1] , and Cymophane
The chrysoberyl, though differing in some characters from the sapphire, yet closely approximates to it in hardness and specific gravity. When pure, it is of a gold yellow color inter-mixed with green, exhibiting a peculiar richness of tint, and in lustre yields only to the brilliant.
It occurs in Brazil, in the alluvial soil, associating with diamonds, usually in grains or rounded pieces, and sometimes in crystals: a stone of twenty carats is rarely met with. In that country it is esteemed the most valuable of all colored stones; and although but recently introduced into Europe, it is rapidly rising in public estimation.
The high lustreand exquisite polish which it is capable of receiving, enables it to sustain a competition with the yellow diamond; and so great is its brilliancy by candle-light, that while the transcendant splendor of the diamond destroys the effect of other stones, this is able to support its presence with unimpaired beauty.
This gem is very difficult to be cut, and few lapidaries are capable of doing justice to it. The Chrysolite is the only colored stone that shows to the greatest advantage when formed into brilliant; but thin stones must be cut in steps.
CYMOPHANE, or OPALESCENT CHRYSOBERYL
Is a chatoyant variety of the preceding gem; it emits a luminous white ray, which changes its position according as the stone receives the light. Its principal estimation in the eye of the connoisseur arises from that circumstance, which on the other hand renders it of little value to the jeweller, the brilliant translucency of the chrysoberyl being more esteemed by the public. The Cymophane is generally cut en cabochon, that it may better shew the play of light from whence it derives its name.
- ↑ The common Chrysolite is a different substance, very inferior in hardness.