2. If bubbles are present in artificial material they will be round or rounding.
3. Artificial material will always have curving parallel striæ within it.
4. The surface finish of artificial material is seldom or never equal to that of natural material.
It ought not to be necessary to add that material from either source may be cut to any shape, and that artificial rubies may be seen in most Oriental garb, hence all specimens should have applied to them the above tests regardless of the seeming antiquity of their cut or of their alleged pedigree.
LESSON XVI
HOW TO TEST AN "UNKNOWN" GEM
Having now considered separately the principal physical properties by means of which one can identify a precious stone, let us attempt to give as good an idea as the printed page can convey of how one should go about determining to what species a gem belongs.
Signs of Wear in an Emerald. To make the matter more concrete, and therefore more interesting, let us consider a real case, the most recent problem, in fact, that the author has had to solve. A lady of some wealth had purchased, for a large sum, a green stone which purported to be an emerald. After a few years of wear as a ring stone she noticed one day that the stone had dulled around the edges of its table, and thinking that that ought not to be the case with a real emerald, she appealed to a dealer in diamonds to know if her stone was a real emerald. The diamond merchant told her frankly that, while he was competent in all matters pertaining to diamonds, he could not be sure of himself regarding colored stones, and advised the lady to see the author.