Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/45

  means of distinguishing diamonds from inferior substances, though highly useful, such as the polarisation of light, electricity, specific gravity, combustion, &c. can rarely be resorted to, except in the laboratory of the philosopher, and are little available to the purchaser of diamonds. The safest and most efficacious criterion for detecting flaws in brilliants, or, in a word, faulty diamonds, is tact, resulting from vigilant attention and habit,

 SECT. II.

Commercial Value of Diamonds.

the great or wholesale trade there is but little fluctuation in the price of those diamonds which may be termed stones in general demand. I will begin with brilliants, from a 