ase may be round, or oval, or square, or cushion shape,
or heart shape or of any regular form. The top is always smooth and
rounding and unfacetted. The relation of the height or thickness to the
length or width may be varied to suit the size and shape of the rough
piece or to suit one's ideas of symmetry, provided the material be an
opaque one, such as turquoise or lapis lazuli. If, however, the material
is transparent the best results in the way of the return of light to the
front, and hence in the display of the color of the material, are had if
the thickness is about one half the spread.

[Illustration: FIG. 11.--CABOCHON CUTTING.]

This relation depends upon the refractive index of the material, but as
most color stones are of somewhat similar refractive indices, the above
proportions are sufficiently accurate for all. The object in view is the
securing of total reflection of as much light as possible from the flat
polished back of the stone. Cabochon stones are sometimes set over foil
or on polished gold to increase the reflection of light.

The path of a ray of light through a cabochon cut stone is closely
similar to that through a rose cut diamond [see cut (c) of Fig. 12 for
the latter.] Like the rose cut, the cabochon cut does not give much
brilliancy as compared to the brilliant cut. Cabochon cut stones,
however, have a quiet beauty of color which commends them to people of
quiet taste, and even fine rubies, sapphires, and emeralds are
increasingly cut cabochon to satisfy the growing demand for fine taste
in jewels. The East Indian has all along preferred the cabochon cut for
color stones, but possibly his motives have not been unmixed, as the
cabochon cut saves a greater proportion of the weight of the rough stone
than the more modern types of cutting.

Garnets, more than other stones, have been used in the cabochon cut, and
when in that form are usually known as _carbuncles_ (from carbunculus, a
glowing coal). Any other fiery red stone might equally well be styled a
carbuncle, especially if cabochon cut.

[Illustration: FIG. 12.--ROSE CUTTING.]

Scientific rubies look very well in the cabochon cut.

Fig. 11 shows in (a) and (b) the front and top of the usual round
cabochon. Cut (c) of the same figure gives the front elevation of a
cabochon which will light up better than the usual round-topped design.
In the round-topped type the central part of the top is so nearly
parallel to the back that light can