here, however, of the
fine glass imitations, which, while lacking the variety of true emerald,
because of lack of dichroism, are nevertheless of a color so nearly like
that of the emerald that no one should attempt to decide by color alone
as to whether a stone is genuine or imitation emerald. If a hardness
test shows that the material is a genuine hard stone and not a paste,
then one who is well accustomed to the color of fine emerald can say at
once whether a stone is a fine emerald or some other hard green stone.
Where the color is less fine, however, one might well refuse to decide
by the color, even when sure that the material is not glass, for some
fine tourmalines approach some of the poorer emeralds in richness of
color.

THE "SCIENTIFIC EMERALD" FRAUD. No "scientific" emeralds of marketable
size have ever been produced as far as can be learned. Many attempts to
reproduce emerald by melting beryl or emerald of inferior color have
resulted only in the production of a beryl glass, which, while its color
might be of desirable shade, was softer and lighter in weight than true
emerald. It was also a true glass and hence singly refracting and
without dichroism, whereas emerald is crystalline (not glassy or
amorphous), is doubly refracting, and shows dichroism.

Do not be misled, then, into buying or selling an imitation of emerald
under the terms "synthetic," "scientific," or "reconstructed," as such
terms, when so used, are used to deceive one into thinking that the
product offered bears the same relation to the true emerald that
scientific rubies and sapphires bear to the natural stones. Such is not
the case.

About the most dangerous imitation of the emerald that is ever seen in
the trade is the triplet that has a top and a back made of true but pale
beryl (the same mineral as emerald, but not of the right color) and a
thin slice of deep emerald green glass laid between. This slice of glass
is usually placed behind the girdle so that a file will not find any
point of attack. The specific gravity of the triplet is practically that
of emerald, its color is often very good, and it is doubly refracting.
It is thus a dangerous imitation. (See Fig. 8.)

EMERALD TRIPLETS. A careful examination of one of these triplets, in the
unset condition, with a good lens, will reveal the thin line of junction
of the beryl with the glass. (The surface lusters of the two materials
are enough different for the trained eye to detect