122 The Spinel and Balas Ruby.
natives of India call the spinel Lai Rumani, or the pomegranate ruby,
and ascribe to it valuable medicinal properties. The spinels and balas
rubies, which are identically the same gems—the term spinel being
applied to those of deeper hue—are frequently sold in error or by fraud
for the true ruby; on the other hand, instances have occurred where a
true ruby of pale colour has been sold for a spinel or balas ruby.
any one acquainted with the characteristics of these jewels, the
mistake is impossible; the hardness of the ruby is far greater, and its
specific gravity considerably more, and nothing can be easier than to
verify these facts. An unset stone can be tested by taking its specific
gravity; or if set, by attempting to scratch a sapphire with it; or by observing the refraction, which also differs, as a glance at Table A will at once show.
spinel is also occasionally mistaken for the garnet, on account of the
similarity of colour in some of the specimens; still more frequently
for the jacinth, from a like reason. Both these gems, however, are of
inferior hardness; besides which, the jacinth possesses a strong
double refractive power, whilst that of the spinel is single. The brown
topaz, which is somewhat similar, may readily be distinguished by its
property of acquiring electricity when heated.
the Middle Ages, the same supernatural powers were attributed to this
stone as to the true ruby. Elianus, an ancient author who wrote a
natural history of animals, relates that a stork once presented a wo-