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THE DIAMOND
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term,
" off-color," means that the ideal purity of the stone is destroyed by
a taint of color. As generally applied, it means by a tinge of yellow
or brown. As popularly understood, it refers to yellow only.
To
judge the color of a diamond, endeavor to get an unobstructed light, a
north light if possible. Do not hold it in the fingers, but by diamond
tweezers, or in the crease of a diamond paper, as to put the breath on
it properly, it must be cold. Then breathe quickly with a slight puff
upon the face of it. This casts a mist on the stone for a second or
two, and enables one to see the front color without the confusion which
arises from its reflective and dispersive powers. Having noted this,
turn the stone in the paper edge-wise to the eye, and partially close
the paper over it to ward off outside inÂfluences. The body color of
the stone can then be seen. If it is a blue-white stone, try it in
various positions and lights and under a loup, watching closely all
parts of the stone for a tinge of color other than blue. If there, it
will be seen at some angle and will be prominent in some light. If
found, the color is false.
Under
artificial light, diamonds with a tinge of brown appear dark; yellow is
much less perceptible than by daylight; gem canaries even cannot then
be distinguished from ordinary stones. Some fancy mixed color stones
become strangely transformed. There are specimens, green to gold in
daylight, which change to brown and red by artificial lights. Under an
arc light, some blue stones lose color, and others not so blue assume a
deep violet hue, very beautiful.
Other things being equal the relative market values of color in the diamond are about as follows:
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