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SPINEL.
Spinel resembles ruby in color, but in most other respects is
wholly different. It is softer, 7.5 to 8, and lighter, 3.5 to 3.7, also
not dichroic, showing the same color in all directions, and single re-
fracting. Its lustre, like ruby, is vitreous, and it takes a brilliant
polish, but not equal to ruby.
It is said that all red spinels have a tinge of yellow reflected from
the interior of the stone which absolutely distinguishes them from
true ruby. The deeper the color, if clear, blood-red, poppy-red, car-
mine, the more highly prized. This is the gem color.
Spinels of a light shade of rose inclining to violet are referred
to as balas rubies. Rose-colored topaz closely resembles this variety,
but topaz is double refracting and strongly dichroic. Spinels tending
towards purple in tint suggest, even if paler, the almandine of the
garnet tribe. There is also a spinel which comes near the amethyst
in color, and is often sold as such, though rarer and more valuable.
The spinel of a pronounced shade of yellow is called rubicelle.
It may be orange-red, and often accompanies topaz in Minas Novas,
Brazil, where it is known as vinegar-spinel, on account of its yellowish
red. The name vermeille, applied by the French to certain garnets,
is likened to rubicelle. This color, in garnets at least, is considerably
more valued than it used to be, since the hyacinth has
again come to the fore.
Fine spinels are more abundant than fine rubies, because more
free from defects. Small ones are plenty, but those of large size,
weighing from eight to ten karats, are rare. The large "Black
Prince Ruby" in the English crown is not a ruby, but a spinel. It
was presented to the Prince by Don Pedro, King of Castile, and worn
in his helmet by Henry V. of England at the battle of Agincourt. It
is cut en cabochon and has a hole showing its Indian origin drilled
through it which has been plugged up by a smaller stone. For long
it was thought to be a ruby.
Spinels were found by Marco Polo, as early as the thirteenth
century, in Badakshan. They are also found in Ceylon, Burmah,
Australia, and with rubies and sapphires in Siam. In the United
States they are practically non-existent, except green spinels, some
transparent and used as gems. Such have been taken from North
Carolina. It is considered remarkable that they are not found with
sapphires in Montana.
Twinned spinels, two faces with one back, are so common that
other minerals, including diamonds, are said sometimes to be twinned
"according to spinel law." Often one of a twin adjoins a third, and
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