HE true or Oriental Cat's Eye is a rare variety of the Chrysoberyl or Cymophane—a
stone of extreme hardness, in this respect being only inferior to the
Diamond and the Sapphire-It is characterized by possessing a remarkable
play of light in a certain direction, resulting, it is supposed, from a
peculiarity in its internal structure, which appears to be minutely
striated. This ray of light, or " line " as it is termed by jewellers,
shines in fine and well-polished specimens with a phosphorescent
lustre. In India the lines of light are called betas, and the price increases according to these " betas."
The
Chrysoberyl Cat's Eye comes principally from Ceylon, where it is found
in company with Sapphires, Zircons, and other gem-stones ; and it has
also been found in China. It is of various colours, ranging from
pale-straw colour through all shades of brown, and from very pale
apple-green to the deepest olive. Some specimens, much sought for by
Americans, are almost black. The line, no matter what ground-colour the
stone may possess, is nearly always white, and more or less iridescent
; occasionally, but very rarely, however, the line is of a golden hue.
This lustre is most beautiful when seen in full sun-light, or by
gas-light, when the lines become more defined and vivid.