Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/136

 CYMOPHANE, or OPALESCENT CHRYSOBERYL 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.