86 A Book of Precious Stones
9
5-16 carats at $33,000, and Mr. E. W. Streeter, the London jeweller and
author, records a purchase price of about $50,000 for a cut ruby of 32
5/16 carats.
The
common faults of rubies are lack of clearness; the presence of "
clouds," also termed silk, especially in light-coloured stones; patches
which resemble milk ("chalcedony patches"); internal cracks and
fissures ("feathers"); and the colour being unequally distributed.
From
the beginning of its history the main supply of the beautiful ruby gem
has been from a small territory in upper Burma, whence, also, have come
those of the finest quality. The centre of this mining region and the
ruby trade is the town of Mogok, ninety miles north-north-east of
Mandalay. The mining district ranges from four thousand to nearly eight
thousand feet above sea-level, but, despite its altitude, this
forest-covered region proves unhealthy for Europeans. The principal
mines are in two valleys in which are the towns of Kathay and Kyatpyen.
Rubies
and the minerals with which they are associated, such as spinel, are
here found in a mother-rock of white, dolomitic, granular limestone or
marble, of the upper Carboniferous age. These rocks have been altered
by contact
