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CHAPTER IX. ALEXANDRITE.'
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HIS
stone was named after the Czar of Russia, Alexander II., having been
discovered on his birthday, in 1830. It owes its celebrity to its
prominent hues of red and green, and as these are the
military colours, the stone became much sought after in Russia. The
Russian Alexandrite can rarely be shown to the best advantage in
consequence of defects of structure, as it is usually flawed with
crevices which make successful cutting and polishing extremely
difficult. The variety found in Ceylon is more easy of manipulation.
Alexandrite
is especially remarkable for its strongly marked difference of colour,
according as it is viewed by natural or by artificial light. The finest
stones present a bright green, or deep olive green colour, by daylight
; whereas, at night, artificial light, such as that of gas or a candle,
brings out a soft columbine red or raspberry tint, or purple. It has
been said that the Alexandrite is an emerald by day and an amethyst at
night.
The Alexandrite is strongly dichroic, while some varieties are even trichroic.
Chemical
analysis shows that the Alexandrite is a variety of Chrysoberyl. The
author has seen, in the course of his experience, two or three stones
with a perfect Cat's Eye line, yet subject to the characteristic change
of colour by artificial light : such stones are called Alexandrite Cat's Eyes, In order to display the line of light, it is, of course, necessary to cut the stone en cabochon instead of facetting it.
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