_Hardness of the Stones_ One reason for the pre-eminence of the diamond is its indestructibility. It is by far the hardest of all stones. Setting the standard of the diamond at ten, a table has been made of descending hardness. The whole numbers on this scale are marked as follows: 10 diamond 9 corundum 8 topaz 7 quartz 6 feldspar 5 apatite 4 fluorspar 3 calcite 2 gypsum 1 talc It is at once obvious that few of these are precious, or even semi-precious, stones. What must be noted is that this list is not a proportionate scale; that is, it indicates order, but by no means any specific degree of hardness. The difference in hardness between the diamond and its neighbor, corundum, is greater than that between corundum and talc. The best that can be said is that, as they are arranged, each one can scratch all those listed below it. Thus there is no other stone that can scratch a diamond. The old saying “diamond cut diamond” means that two champions are evenly matched, and diamonds can be cut and polished only in this fashion. A wheel of corundum or other substance is coated with diamond dust; when this is applied to a diamond stone, an equal process of attrition takes place; diamond dust is worn off both the wheel and the stone. This dust, of course, may be used for further cutting and polishing to make the finished stone. The cutting referred to here is the shaping of the facets and the surfaces of the stone; for most crystalline formations, however hard, are brittle; that is, they may be split or cleaved along the lines of the crystal edge. This accounts for both the possibility and the danger of cleaving the raw diamond. Formed under tremendous pressure beneath the surface of the earth, a diamond may be distorted in its growth; it may be an unshapely and often a fairly large stone, which must be cleft to a proper shape and size for setting. This cleaving, effected by a single hammer tap, is made only after minute examination and re-examination—sometimes a year’s pondering—by an anxious expert. After this cleavage, a diamond will be much smaller than when it was mined, but it counterbalances the loss of size by the greater brilliance and beauty the new shape discloses. The Kohinoor diamond was over 700 carats when it was found; when cut it was no more than 186⅙ carats; and since then it was recut, as a brilliant, to its present weight of 106⅙ carats. Sculpture has been defined as the process of removing the excess from the marble statue already within the block; how much more this is true of the precious stone, which the lapidary releases from its dull confinement!