reflection.
Sent on according to the laws of light at the same angle as that of the
incidence, they pass through the body of the stone to meet again angles
of total reflection, and are again carried on until they emerge
finally from the front of it. Look into the face of a diamond and you
will see the imprisoned light scintillating on the burnished facets at
the back. Turn it as you will and wherever you look, there is the sheen
of light playing over transparent walls, adamantine to it; an
imprisoned star beneath a covering of limpid dew.
High
refractive power is accompanied by a corresponding power of
dispersion, consequently the dispersive power of the diamond is much
greater than that of most mediums. It is as .058 to .021 in glass. In
the refraction of a ray of white light, it is really broken into its
constituent color rays, which are spread out spec-troscopically. The
index of refraction given is the mean of the color band. To this high
power of dispersion is due the effect of color coming to the eye with
the emission of flashlights of white light which has traversed the
stone and been split up into its constituent colors, by refraction.
Many expect to see this color play from the diamond under any light but
sunlight and some artificial lights only are the source of it. Nor is
the eye always sufficiently quick to catch it, though an illustration
can be made, by holding a diamond to receive the sun's rays, and a
sheet of paper at the proper angle to catch them as they are reflected
by the stone. Then the brilliant rainbow colors will appear.
As
the diamond crystallizes in the isometric system, in which the axes are
equal, the refraction is normally single, though occasional stones,
from extraordinary
