the
difficulty of describing the colour quality of this stone greater.
There is also some prismatic " fire " in the stone, and much internal
reflection of light, while its surface lustre lies between resinous
and vitreous. These four properties give to the red of the ruby a
peculiar richness, which the two other species of precious stones—the
spinel and the garnet—which come nearest to it in colour, do not
equally possess. The two reds which make up the colour transmitted by
the ruby do not differ much, but yet they help to impart, to a properly
cut stone, a delicate variation of hue which is not present in any
other red stone, nor in any imitative substance. The dichroiscope,
consequently, never fails to discriminate between a ruby on the one
hand and a spinel or a garnet on the other. The two latter stones are,
of course, softer than the ruby, and the former is always lighter, that
is, of less specific gravity. For the ruby and the whole of the
corundum family of stones have the specific gravity of 4, and a
hardness which is nearly, and in some cases quite, 9 on the
mineralogical scale.
One
of the happiest uses of the ruby is in the form of an inlay, in certain
gold vessels of Indian origin. The external surface of these vessels is
covered with a system of interlacing ridges and furrows. The rubies,
generally small, oval, and cut en cabochon, are set along the
furrows. Thus they are much protected from the chance of dislodgment,
while the effect they produce, of a rich deep crimson groundwork over
which a gold netting has been thrown, is in perfect harmony with the
materials and their workmanship. For, naturally, the metal gold, when
pure, or nearly pure, throws a ruddy tint when light is reflected from
surface to surface; witness the interior of gilt vessels. The same
thing occurs in the golden furrows of which we have spoken, where the
rubies seem to rest in a golden sheen, of a hue in which the yellow,
and orange, and red elements, now one and now another, appear to
prevail. The gold should not be burnished where much contrast between
the metallic surfaces and the rubies is desired, but
