A treatise on diamonds and pearls. In which their importance is considered: and plain rules are exhibited for ascertaining the value of both; and the true method of manufacturing diamonds / [David Jeffries].

  • Jeffries, David
Date:
1751
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on diamonds and pearls. In which their importance is considered: and plain rules are exhibited for ascertaining the value of both; and the true method of manufacturing diamonds / [David Jeffries]. Source: Wellcome Collection.

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    good and bad blended together, which are worthy the expence of ma- nufaCtury. For example, fuppofe the value of a rough Diamond of two O carats, at the rate of 2 /. per carat, fhould be required ; the rule is, fir ft, to multiply 2 by 2, which makes 4, the fquare of its weight ; then, multiply the product of 4 by 2 /, the price of one carat, that makes 8 /. which is the true value of a rough Diamond of 2 carats. To make this rule applicable to mamtfaEiured Diamonds it will be neceffary to afcertain what wajle, or lofs of weight, will be fuftained in manufacturing them. And here it may be advanced as a matter of fact, that half the weight will be loft; confequently, doubling the weight of any manufactured Diamond, ren¬ ders the rule of the fame ufe to fhew
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