GEMS AND PRECIOUS STONES. 25
Oriental Amethyst, or Purple Sapphire.
This
is the true amethyst, and is distinguished by its amethystine or purple
colour. The name amethyst is now generally given to the purple variety
of quartz, and it is as well to bear this in mind, because the quartz
amethyst is comparatively a common mineral, and not of much value,
while the purple corundum (the true amethyst) is rare, and far more
valuable. The difference in hardness and specific gravity will readily
determine these minerals, besides the quartz variety has less
brilliancy.
There
are fine specimens of the oriental amethyst at Dresden (Germany), and
in the Vatican are engraved intaglios of this gem, of a very early date.
Oriental amethyst has not yet been recorded from New South "Wales.
Oriental Emerald, or Green Sapphire.
This
is the green variety of corundum, and must not be mistaken for the
emerald, which is a totally different mineral. When of good colour, it
is greatly superior in brilliancy and lustre to the ordinary emerald,
and on account of its hardness and great rarity, is far more valuable.
The oriental emerald is stated to be fairly plentiful in Northern
Gippsland, Victoria. At the Melbourne Exhibition of 188S, Professor
Liversidge exhibited two cut specimens of this gem ; these were found
at Bingera, in this colony. Greenish sapphires are not uncommon in the
New England district of this Colony.
Oriental Aquamarine.
When
the green variety of corundum is very pale coloured, it is called
oriental aquamarine. It is distinguished from the ordinary aquamarine
(which is a variety of the beryl), by its superior hardness and
specific gravity, and by being far more brilliant. When the tint is
inclining to olive, this stone is known by the name of oriental peridot.
Oriental Topaz, or Yellow Sapphire.
This variety of corundum is more plentiful than the green and purple varieties ; it is of a yellow tint, generally inclining to a light straw-colour ; it is a very
brilliant stone, but of little value commercially. It, and the yellow
diamond, might be mistaken for each other ; but the difference in
hardness and in crystalline form distinguishes them. Oriental topaz
also usually shows dichroism, which property is wanting in the diamond.
Its difference from yellow zircon may be determined by the inferior hardness of the latter, by the difference in crystalline form, and other tests.
Asteria, or Star Stone.
This
name was given by the ancients to certain species of precious stones,
principally corundums, which, having a peculiar structure, displayed
rays of light in the form of a six-pointed star.
Romantic
people placed a high value upon these star-stones, considering them a
powerful love charm, and tradition tells us that one in a signet ring
was worn by Helen of Homeric fame, so that it is not improbable that
this asteria was connected (although no doubt unintentionally) with the
calamities of the Trojan war.
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