SIMPLE DIAMOND TESTS.

Gisborne Times, Volume XXV, Issue 2069, 21 December 1907, Page 4 (Supplement)

SIMPLE DIAMOND TESTS.

“There are few' persons,” remained a jeweller, “who are able to purcliaso a diamond on the strength of their owm knowledge and observation and without, placing implicit confidence in the man who sells tlio stone. It is a fact that even pawn-brokers have often been taken in by jewellery and precious stono fakers. “Although it takes many years of actual observation and experience before one can become a diamond cxpert, there are a few simple tests which will considerably aid a buyer of diamonds. One test is to prick” a needle hole through a card and look at tho hole through a doubtful stono. “If the latter is spurious two lioles will bo seen, but if it is a diamond only one hole will be visible. Every imitation stone wliiciliresemblesii diamond gives a double reflection, while the diamond’s refraction is single. “This is a delicate test, because it is difficult to see even a sharp and defined objoct through a diamond. The single refraction of the diamond also allows ono to determine an uncertain stone. “If the finger it placed behind it and viewed through the stone with a watchmaker’s glass, tlie grain of the skin will bo plainly seen if the stone is not a diamond. But if it is a diamond the grain of the s'kin will not bo distinguished at all. “A diamond in solid settings may be identified in the same manner.. If genuine, tho setting at the back cannot. bo discerned, but if it is an imitation stono the foil or setting will be seen.

“There is no acid which has any perceptible effect upon a genuine diamond. Hydrofluoric acid, if dropped on a’ stone made of glass, will corrode it, but will not affect a diamond one way or the other. A trained eye can see the hardness of a diamond, whereas the imitations appear soft to tho vision of tho experts.”