ten done.

It will be the purpose of this lesson to attempt to set forth as clearly
and as briefly as possible what constitutes good usage in the naming of
the principal stones, and also to point out what incorrect usage is most
in need of being avoided.

To cover the subject systematically we will adopt the order of hardness
that we did in discussing mineral species in Lesson XVIII.

FANCY DIAMONDS. Beginning with the hardest of all gems, the _diamond_,
we have no difficulty as regards naming, as all specimens of this
mineral, regardless of color, are called diamonds. When it is necessary
to designate particular colors or tints, or differences in tint,
additional names are used--for example, all diamonds of pronounced and
pleasing color are called "fancy" diamonds in the trade. Certain of
these "fancy" diamonds are still further defined by using a name
specifying the color, as, for example, "canary" diamonds (when of a fine
bright yellow), or "golden fancies," when of a fine golden brown, or
"orange," or "pink," or "absinthe green," or "violet," as the case may
be.

NAMES OF VARIOUS GRADES OF WHITE DIAMONDS. The great majority of the
diamonds which come on the market as cut stones belong, however, to the
group which would be spoken of as white diamonds, but many qualifying
names are needed to express the degree of approach to pure white
possessed by different grades of these diamonds. Thus the terms: 1,
_Jaegers_; 2, _Rivers_; 3, _Blue Wesseltons_; 4, _Wesseltons_; 5, _Top
Crystals_; 6, _Crystals_; 7, _very light brown_; 8, _Top Silver Capes_;
9, _Silver Capes_; 10, _Capes_; 11, _Yellows_, and 12, _Browns_,
describe _increasing_ depth of color, and hence _decreasing_ value in
diamonds.

POPULAR NAMES. Certain more popular names for diamonds of differing
degrees of whiteness may next be set forth. The term "blue white" (a
much abused expression, by the way) should be applied only to diamonds
of such a close approach to pure whiteness of body substance, as seen
on edge in the paper that, when faced up and undimmed, they give such a
strong play of _prismatic_ blue that any slight trace of yellow in their
substance is completely disguised, and the effect upon the eye is
notably blue. This would be the case with stones of the grades from 1
through 4 in the list above. Grades 5 and 6 might properly be called
"_fine white_," and grades 7, 8, and 9 simply "_white_." Grade 10 is
frequently spoken of as "_commercial white_