Noble
corundum of other colors than those of blue and red is not of abundant
occurrence, nor is it ordinarily as highly prized as are the sapphire
and ruby. Colorless sapphire, or leucosapphire, is sometimes used as a
substitute for the diamond, from which it can readily be distinguished
by its lower hardness and higher specific gravity.
Certain
specimens of both sapphire and ruby, but especially the former, exhibit
when polished a six-rayed star. This appears as beams of light,
radiating from a center which changes in position as the stone is
turned. Such stones are called star, or asteriated sapphires, or
rubies, and are highly prized. They are usually cut with rounded
surface, as this best brings out the figure. The cause of the
star-shaped figure is generally supposed to be the total reflection of
light from countless microscopic cavities in the stone, which are
arranged parallel to the faces of a six-sided prism. Some authorities
believe, however, that multitudes of twining lamellas similarly
arranged cause the appearance.
Burton,
the African traveler, is said always to have carried a star sapphire
about with him, as a means of winning respect from the barbarous
peoples among whom he journeyed. The savages believed that the stone
must be a talisman of great power and feared to incur its owner's
enmity.
Sapphire
is a word which is the same in nearly all languages, a fact which
testifies to the ancient use of the stone. In Chaldean, Hebrew, Greek,
and Latin the word has the same form as in modern tongues. In early
times sapphire was believed to be a destroyer of poison, so that if put
into a glass with a spider or venomous reptile it would kill it. It was
regarded also as a remedy against fevers if placed on the heart, or
soaked in vinegar and the extract administered. The wearer of a
sapphire was rendered by it chaste, virtuous, pious, devout, and wise.
