lly with a good lens they
strongly resemble the flaws in natural emerald.

I have thus gone into detail as to how one may distinguish true emerald
from tourmaline and from glass imitations because, on account of the
high value of fine emerald and its infrequent occurrence, there is
perhaps more need for the ability to discriminate between it and its
imitations and substitutes than there is in almost any other case. Where
values are high the temptation to devise and to sell imitations or
substitutes is great and the need for skill in distinguishing between
the real and the false is proportionally great.

3. The demantoid garnet (often unfortunately and incorrectly called
"olivine" in the trade) is usually of an olive or pistachio shade. It
may, however, approach a pale emerald. The refraction being single in
this, as in all garnets, there is little variety to the color. The
dispersion being very high, however, there is a strong tendency, in
spite of the depth of the body color, for this stone to display "fire,"
that is, rainbow color effects. The luster, too, is diamond-like as the
name "demantoid" signifies. With this account of the stone and a few
chances to see the real demantoid garnet beside an emerald no one would
be likely to mistake one for the other. The demantoid garnet is also
very soft as compared with emerald (6-1/2 as against nearly 8).

4. True olivine (the peridot or the chrysolite of the trade) is of a
fine leaf-green or bottle-green shade in the peridot. The chrysolite of
the jeweler is usually of a yellower green. Frequently an olive-green
shade is seen. The luster of olivine (whether of the peridot shade or
not) is oily, and this may serve to distinguish it from tourmaline
(which it may resemble in color). Its double refraction is very large
also, so that the doubling of the edges of the rear facets may easily be
seen through the table with a lens. The dichroism is feeble too, whereas
that of tourmaline is strong. No one would be likely to confuse the
stone with true emerald after studying what has preceded.

5. Bluish-green beryl (aquamarine) is usually of a pale transparent
green or blue green (almost a pure pale blue is also found).

Having all the properties of its more valuable variety, emerald, the
pale beryl may, by the use of these properties, be distinguished from
the pale blue-green topaz which so strongly resembles it in color.

6. Green sapphire seldom even approaches emerald in finen