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next.
The other colors occur rather sparingly, green having been almost
unknown until the discovery of the Montana sapphires. The nature of the
coloring ingredient of the different varieties of corundum is not
known, but there is some reason for believing it to be chromium, for
Fremy obtained artificial red and blue corundum by mixing chromium with
his other ingredients, after many other attempts to obtain the desired
color had failed.
Red
corundum varies in hue from rose to deep red. That of the latter tint
is the true ruby, the color known as pigeon's blood being most highly
prized. Faultless stones of this color have long been the most valuable
of gems, exceeding the diamond in price, weight for weight. At the
present time they are worth between $2,000 and $3,000 per carat. The
writer recently saw a ruby of nine carats in the possession of a
Chicago jeweler which is valued at $25,000, and one of eleven carats
is, reported to have been lately sold for $80,000. But few rubies
exceeding ten carats are known. The King of Pegu is reported to have
one the size of a hen's egg, but as no one has ever seen it the story
may well be doubted. In the crown of the Empress Catherine was,
however, one the size of a pigeon's egg. There is also a large uncut
ruby in the British crown, said to have been given to Edward, Prince of
Wales, by the King of Castile, in 1367. Ruskin calls it the loveliest
precious stone of which he has any knowledge. This is probably,
however, a spinel ruby, not a corundum ruby.
The
chief home of the true ruby is Burmah. From its mines and those of Siam
and Ceylon have come practically all the world's supply. The most
important Burmese mines are in Mogouk, ninety miles north of Mandalay.
The rubies were evidently formed here in limestone, which is now much
decomposed, and seem to have been the result of metamor-phism of the
limestone by the entrance of eruptive rocks. The ruby-bearing earth is
known as " byon," and the gems are obtained from it by washing. They
are usually in the form of more or less complete crystals. The mines
have been worked since the British occupation of Burmah in 1886, by a
British company, and there can be little doubt that a desire to acquire
these mines was one reason for the occupation. The mines have not
proved very profitable, however, and only within the last year or two
has the company been able to pay any dividends. The hope of success has
lain in the introduction of machinery for washing the byon more cheaply
than it could be done by the primitive native methods, and it is now
believed by the introduction of an electrical power plant that this has
been accomplished. This company now produces at least one-half the
annual yield of rubies of the world.
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