nine
lines by six. In the last century the two most famous opals belonged,
one, round and very brilliant, to the amateur Fleury; the other,
fascinatingly vivid—an oval of the dimensions of Fig. 73—to the
distinguished financier D'Augny.
The fire opal is
furnished principally by Mexico. Its colour, more pronounced than that
of the oriental opal, and the carmine or vinous red tint of its fires,
permits it to be easily recognized. At its maximum of effect the fire
opal is brilliantly lovely; but its beauty is easily deteriorated by
atmospheric influence.
The common opal displays
very little fire; its colour is milk-white, which, joined to a texture
extremely homogeneous, renders it semi-transparent.
It is said that since the opal was introduced by Sir Walter Scott into his novel of Anne of 'Geierstein, its
favour has sensibly declined; and the gem, considered by the ancients
to exercise the combined virtues of the amethyst, ruby, and emerald, is
branded now as " an unlucky stone."
ENGRAVING UPON THE OPAL.
The
work of engraving upon the opal is very difficult, and often quite
impossible, on account of the thousand fissures of the stone. Besides,
the fine effects of light which give it special value are
