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GEMS.
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the
day, and insisted that an attentive observer might use it as a sundial.
In Germany even now it is believed that, when offered as a love gift,
it remains unchanged while love lasts, but loses its colour when
affection declines. But if the colour of the Western and that of the
fossil Oriental turquoise change, it is not so with the aluminous
turquoise, which always remains the same.
Fossil turquoises change colour only on the surface, so that they can regain it by means of the wheel.
Not
so with the Western turquoises, which, changing altogether, can only
for some days be made to regain their lost colour by dipping them in a
solution of oxide of copper. They are then called bathed turquoise, and are of very little value.
Some people think that the turquoise is the stone which the ancients called callaie, and
is thus described by Pliny : " The callaie grows in the islands of
Mount Caucasus, but is spongy and full of spots : that from Caramania
is clearer and bettet,' In both places it is found in inaccessible and
cold banks protruding in the form of an eye, which does not appear to
have been produced in the stone, but fastened on it. It can be cut and
worked, but is fragile. When set in gold, no jewel looks so well. The
handsomest .lose their colour in oil, grease, or wine ; the worst
preserve theirs best. No stone can be better imitated in glass than
this."*
Theophrastus is more explicit on this subject, when * ' Nat. Hist.' xxxvn. viii. 33.
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