of
a yellowish-green, yellowish-brown, blackish, and hyacinth-red colour.
It derives its name from possessing a peculiar opalescent lustre,
between resinous and vitreous, which shows most strongly when cut en calochon. When
held towards the light, it resembles the contracted pupil of the eye of
a cat; this singular effect being caused by fibres of amianthoid
asbestos running parallel across the stone. It is usually translucent,
sometimes quite transparent, very easily broken, and the fracture
imperfectly conchoidal. Before the blowpipe it loses its lustre and
transparency, and in powder is fusible, although with difficulty. It
occurs in a massive form in Bavaria, the Hartz Mountains, and in
Bohemia; but the good quality only comes from Ceylon and the Malabar
coast, where it is found in small rounded pebbles. The cutting is
usually performed in Ceylon, and when exhibiting the cat's-eye
peculiarity in perfection, is much esteemed.
This
gem is frequently confounded by jewellers and lapidaries with the true
or chrysoberyl cat's-eye, which they also persist in calling
"chrysolite cat's-eye." The chrysoberyl (termed " cymophane " when
opalescent) is a much more beautiful gem, and may easily be
distinguished by its superior hardness and greater specific gravity.
The
cat's-eye is much used in jewellery for rings and pins, and its value
has tripled in the last ten years. It is impossible to fix any value
which would guide a purchaser, the price being a fancy one, dependent
on the size and beauty of the gem.
