In commerce, a carat diamond is sometimes called a four-grain stone, and a carat-and-a-half stone is six grains, etc., etc.
The weight of the carat being arbitrary, it varies in different countries, some being heavier and others lighter than .205 milligrams.
The writer wrote to three prominent balance-makers in the United States some months ago for their carat standards and was surprised to find that they all differed. This will account for discrepancies in weight resulting between the balances of different makers. Of late there has been a decided movement in Europe, headed by the French Chambre Syndicale of jewelers, in favor of the unification of the carat, so that the weight of a French or Dutch carat will equal that of an English, American, or any other carat. This reform will probably be accompanied by the adoption of the decimal system of dividing the carat, and the discarding of the complicated fractional system.
After having tried the decimal weights for many months, the author can testify to a decided gain in time and accuracy from their use.
Fusibility.
The blow-pipe or dry test for minerals is convenient to apply to small bits or splinters of a stone.
The mineral is either held by a pair of platina-pointed forceps, or powdered and placed on a metal plate or in a glass tube.
Before the blow-pipe, some minerals change color, but do not melt, while others retain their color, or swell up, or break into small particles, or melt into colorless or colored glasses.
The following is the scale of minerals used to test the different degrees of fusibility:
1. Gray Antimony. Fusible in coarse splinters in summit of candle flame without the blow-pipe.