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AMETHYS
The violet, purple to almost pink variety of
quartz is amethyst, an ancient name derived from the Grecmethystos,
meaning not drunken, as it was believ, protect those who wore
it from drunkenness. It is the highly prized variety of quartz.
Appearance The typical color is a rich, violet
often distributed in patches or bands. It can also be . pale,
but is generally the same basic color, withow overtones. It
is given both oval and drop mixed cuts stepcuts, and other
types of cuts used for colored stones Specimens of good color
but with too many inclusions arEcut en cabochon. Stones of
10 or so carats in weight are often found and even larger
ones are not rare. Amethyst normally has good luster and transparency.
Well-formed characteristically colored groups of crystals
(geodes anc druses) are even used in their natural state as
ornaments Distinctive features The distribution of the color,
it striking patches and bands, is characteristic. When the
stones contain inclusions, a series of discontinuous, wavy
parallel lines, visible with a lens, indicates that they are
certainly amethyst.
As with nearly all quartzes, the interference figure has ~
distinctive profile, which usually makes identification immediate.
Quartz may resemble some violet synthetic corundum, but the
latter turns reddish in strong artificial light and full sunlight.
Amethyst can also look vaguely similar to violet cordierite,
which also has a strong, distinctive pleochroism. The much
rarer violet scapolite may look quite similar, and its physical
characteristics are almost the same as those of quartz. Therefore
they can only be distinguished by an expert.
Occurrence The finest amethysts come (in
great quantities) from Brazil and neighboring Uruguay, from
the Unite.: States, Madagascar, and the Soviet Union, India,
Australia South Africa, and many other countries.
Value A few centuries ago,
deep-colored amethyst was highly prized. Its value fell greatly
with the discovery of the large Brazilian and Uruguayan deposits
at the end of the nineteenth century. Now relegated to the
status of a secondary gem, its value is quite low.
Simulants and synthetics Amethyst
was much imitated by colored glass in the past, when it was
more costly Nowadays, despite the limited value of the natural
stone fair quantities of synthetic amethyst are produced,
usinc: the knowledge acquired in the production of synthetic
quartz for technological purposes. The cost of the synthetic
product is not much less than that of the natura gemstone.
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