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92 ' PRECIOUS STONES.
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reliable
test, however, seems to be in the destruction of the stone. The real
Turquoise, on strongly heating in the blowpipe flame, decrepitates
violently and turns brown to black. The artificial production under the
same treatment fuses quietly to a black glass.
The
exact method of their preparation is not known, but seems to consist in
applying great pressure to small quantites of powder having the
composition of Turquoise (hydrous pbosphate of alumina with a trace of
copper oxide); the powder is chemically precipitated, and is in a very
fine state of division. The stones produced by this method are all
small, no large ones having been detected.
"With
increase of knowledge, as each branch of science grows, we may yet live
to see the day when Diamonds will be made on the " while you wait "
system. In these days of scientific marvels, one wonders, not at what
has been done or what is likely to be accomplished in the future, but
what will be left undone. In point of fact, we have almost ceased
wondering at all.
The
more scientific methods of identification have been mentioned
elsewhere, so no mention has been made in this chapter of specific
gravity solutions, refractometers, or the colouring effects of radium
or the Rontgen rays upon the Diamond and Sapphire.
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