Clarification of Refraction. Maybe the surest single technique for recognizing valuable stones
is to discover the refractive file of the material. To one not familiar with the study of
material science this requires some clarification. The term refraction is utilized to depict the bowing
which light goes through when it passes (at any point however a correct point) from one straightforward
medium to another. For instance, when light passes from air into water, its way is bowed at the
surface of the water and it takes another bearing inside the water.
While each diamond stone refracts light which enters it from the air, each stone has its own distinct
capacity to do this, and each contrasts from each other in the measure of bowing which it can bring
about under given conditions. The exact assurance of the measure of bowing in guaranteed
case requires finely developed optical instruments and furthermore an information on the most proficient method to apply a
certain measure of math. In any case, this piece of the work has effectively been finished by
skilled researchers, and tables have been set up by them, in which the qualities for each
material are put down.
The Herbert-Smith Refractometer. There is available an instrument called the Herbert-
Smith refractometer, through which anybody with a little practice can peruse immediately on the
scale inside the instrument the refractive record, as it is called, of any valuable stone that isn't
excessively exceptionally refractive. (Its furthest cutoff is 1.80. This would bar not very many stones of significance,
I. e., zircon, precious stone, sphene, and demantoid garnet.)
Those perusers who wish to make a more serious investigation of the development and utilization of the
refractometer will track down an extremely full and complete record of the subject in Gem-Stones and their
Particular Characters, by G. F. Herbert-Smith, New York; James Pott and Co., 1912. Part
IV., pp. 21-36. The Herbert-Smith refractometer is there portrayed completely, its standard is
clarified and bearings for utilizing it are given. The cost of the refractometer is essentially so
high (obligation included) that its buy probably won't be legitimized on account of the more modest retailer.
Each huge dealer in hued stones, regardless of whether shipper, distributer, or retailer, ought to have
one, as by its utilization quick and precise conclusions of stones might be made, and its utilization
isn't limited to unmounted stones, for any stone whose table feature can be applied to the
surface of the focal point in the instrument can be resolved.