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Previous
to the working of the mines by the English the mining was performed by
domestic labor under control of the native government, all rubies
above a certain size going to the king. Whenever a ruby of unusual size
was found a procession of grandees, with soldiers and elephants, was
sent out to meet it. One of the titles of the King of Burmah was Lord
of the Rubies.
The
Siamese rubies come from near Bangkok, on the Gulf of Siam. They occur
in a clay which seems to be the product of alteration of a basalt.
These rubies are not equal in quality to those of Burmah. Rubies are
also found in the gem gravels of Ceylon, and in 'Afghanistan,
thirty-two miles east of Cabul.
In
our own country ruby corundum is occasionally found in connection with
opaque corundum in Macon County, North Carolina. In the gravels of
Caler Fork of Cowee Creek of this county good rubies are found in
sufficient quantity to reward systematic mining for them. They are
known as "Cowee Creek" rubies.
The
gravels containing them are "washed" by methods described by Dr. J. H.
Pratt as similar to those used in the West for washing gold-bearing
gravels. Both the gravel and the soil which overlies it are washed into
a line of sluice boxes which lead into a sieve box. From the latter the
dirt and fine gravel are. washed away. The material that remains is
shoveled into a rocker, into the bottom of which the rubies, being
heavier, gradually work, and are then removed by hand picking. These
rubies are mostly small, but some gems of three or four carats' weight
and of excellent color have been obtained.
Among the Montana sapphires an occasional red stone is found, but they do not have the choicest red color.
Another
source of rubies is their artificial production, after the method
discovered by the French chemist Fremy. The artificial rubies are made
by heating a mixture of aluminum sesquioxide, carbonate of lime, barium
fluoride, and potassium chromate in a porous clay crucible to a
temperature of 1500° C, and keeping the mixture fluid for eight days.
Well-formed, clear crystals up to one-third of a carat in weight -are
thus produced, which have the hardness and color of native ruby. They
are not considered so valuable as gems as the latter, and can usually
be distinguished by the minute air bubbles which they contain. The
expense of making them is nearly equal to the value of native rubies,
so that their production is likely to be limited.
Other
substitutes for the ruby are garnet, that from South Africa being known
as Cape ruby, hyacinth, red tourmaline, known as Siberian ruby, rose
topaz, sometimes known as Brazilian ruby, and spinel. None
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