The process of cutting the diamond is divided at Amsterdam into several distinct branches, and workmen are educated to perform one part, but not another. Thus the cleaving, the cutting, and the polishing have special operators, who become expert in performing well the parts assigned to them without attempting the others. This ceremony and care adopted by the Jews has undoubtedly produced skilful workmen; but we see no reason why all the parts may not be perfectly acquired by an intelligent mechanic. The art of cleavage, however, requires tact, and ought to include some knowledge of mineralogy. For the particulars of the art of diamond-cutting, we will refer our readers to the interesting chapters by Jeffries, Mawe, and Barbot; but we will, however, briefly mention some of the forms adopted for the diamond, and how they are produced. The table and the rose patterns were the first regular forms adopted by the lapidaries. The first was simply the top of the stone ground flat with a corresponding flat bottom of less area, with its four upper and lower sides parallel to each other. As the light passed through the stone without much refraction, the beauty of the mineral was not developed by this pattern. It has been stated that the rose shape was invented in Paris under the auspices of Cardinal Mazarin, but Tavernier describes the diamonds of Aurungzeb of India as being of the rose-cut. Therefore we must give a more ancient date to the pattern than Mazarin’s day. The form of the rose-cut is simply that of a hemisphere covered with small facets. Its flattened base is therefore admirably adapted for incrustation work, and the foil on which it is generally set serves as a refracting mirror for the entering rays of light. The rose pattern has several names which indicate the number of facets which they may bear. If it has but twelve or less facets it is called an Antwerp rose; if but eighteen or twenty it is a semi-Holland, and a Holland rose if it bears twenty-four facets. At the present time these gems are not in much demand, unless for incrustation work, for which they are superior both in effect and in adaptability to the surface of the object to be ornamented. The form which appears to exhibit the splendors of the gem to the best advantage is that known as the brilliant, and is rightly named from its effects. It was discovered in Italy in the latter part of the seventeenth century by Peruzzi of Venice, which city was then one of the chief gem marts of the world. The conclusions which led to the adoption of the shape were derived from experiments upon colored stones. This form of the brilliant is that of the ancient deep table modified by receiving thirty-two facets above and twenty-four below its girdle. The great relative depth of the gem, aided by the numerous facets of the sides, appears to increase the natural refractive power of the stone by confining, as it were, the rays of light inside of it.