cooling,
however, rubies are restored to their original colour, whereas
sapphires are not. I have not met with any explanation of this
phenomenon.
The
sapphire is slightly harder than the ruby, which stands at number nine
in the scale of mineral substances, or only one degree below the
diamond, hardest of them all.
Another
interesting fact, though at the moment it seems to have no practical
application, is that sapphires when exposed to the action of radium
rays turn first green and then yellow.
There
are stones called "sapphire" which are not the true sapphire. The
ancient world—Egyptians, Assyrians, Babylonians—often knew by the name
of sapphire that other "blue stone", the lapis lazuli. Lapis lazuli is
not a translucent stone like the sapphire, but intensely opaque, and
when of high grade it is of an ultramarine blue, delightful to behold.
The men of old time thought of the opaque blue lapis as masculine and
the translucent blue stone as feminine, seeing sex run through all the
things of creation.
Then
there is the star sapphire, another and this time exclusive child of
Ceylon. Invariably slightly cloudy, it is only in the rarest cases of a
pronounced blue. The best, and indeed the only, way of showing up its
peculiarity, the star, is to cut it en cabochon, i.e., with a convex top. Then, if it is a perfect star stone (Asteria) it should radiate six distinct rays from the apex. A blue stone showing a good star is truly worthy of the gem-lover.
The scientists, of course, have an explanation for the
