A treatise on diamonds, and precious stones, including their history. Natural and commercial / To which is added, the methods of cutting & polishing. With colored plates. By John Mawe.

  • Mawe, John, 1764-1829.
Date:
1823
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on diamonds, and precious stones, including their history. Natural and commercial / To which is added, the methods of cutting & polishing. With colored plates. By John Mawe. Source: Wellcome Collection.

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    It may also be premised, that, in speaking of individual diamonds, we often, for the sake of convenience, use the term stone, “ a beau- “ tiful stone,” “ a bad stone,” which, although not strictly applicable to this substance, is sanctioned by general usage. Diamonds are sold by a particular stand¬ ard, which appears to be universally adopted. The integer of weight is termed a carat, and it is divided into four grains. To prevent the circumlocution arising from the use of two terms, the weight of a diamond is often stated simply in grains. The carat is divided not only into quarters, (or grains), but also into eighths, sixteenths, thirty-seconds, and six¬ ty-fourths, and these minute subdivisions * The carat is an Indian denomination of weight. One hundred and fifty carats and a quarter arc equal to an ounce, Troy.