46 PRECIOUS STONES
the
lighter, or the darker, which has a blackish appearance. The pink
should be a deep, clean color, similar to a pink ruby, and the brown
should be a rich amber-brown.
The best diopsides are very similar to the fine green tourmaline.
Fine moonstones show a blue chatoyant light on a gray background.
The
desirable color in turquoise varies with fashion. At present it is the
tint known as robin's-egg blue. It should always be free from a chalky
appearance, white specks, or other evidence of matrix, and from the
greenish cast of color which is its most common fault. The color should
be even, and the surface show a high polish.
Probably
honey-color is favored by the greatest number of the admirers of the
Oriental cat's-eye, though apple-green, and a rich brown showing an
inner light of golden yellow, are preferred by many. The line of light,
in any case, must be sharply defined, passing straight over the centre
of the dome when presented squarely to the eye, and spreading as it is
turned.
Star
rubies and sapphires are seldom of good color. Their beauty and value
depend mainly on the clearness and even distribution of the rays from
the centre of the dome.
Of
the many stones of varied hues for which there is no standard, it can
be said only that individual taste must decide between them,
remembering always that a clean, rich, decided color, of whatever kind,
is preferable. This includes the fancy colored sapphires and spinels,
zircon, garnets, beryls, etc.
Fancy
stones, especially of the more precious crystalline varieties, are
seldom perfect, but if the flaws or imperfections do not destroy the
brilliancy and distribution of color, they are not accounted of as much
importance as in the diamond. Rubies generally contain clusters of
light or dark-colored spots. Ragged cavities in the surface of the
stone are com-
