FALSE PRECIOUS STONES OF THE NATURAL KIND.
It
is of some importance to examine this subject, because there is a
prevalent belief that all false stones necessarily have glass as their
base, and are consequently of little hardness. People often say, when
their rubies or their topazes are declared false, " But, see, here is a
file; try to scratch these stones; you will not succeed." Very true;
but submit any piece of quartz to the same test, and the result will be
the same.
Since,
as we have said, hyaline or variously coloured quartz is very abundant
in nature, it is easy to procure, at insignificant prices, stones that
perfectly resist the file, and show, often in a remarkable manner,
the whole series of colours that we admire in real precious stones.
Stones
of this kind are very abundant in commerce; it might be said that,
with few exceptions, all those designated as occidental are of this
character, and possess consequently hardly any value.
Another
deception of the same kind consists in passing off a stone of a certain
nature and a certain value, for another stone of a different nature and
a much higher value.
The colourless varieties of sapphire and topaz, which in density, in hardness, and in refractive
