It is an extraordinary thing that the diamond, which is the most limpid and brilliant of all earthly stones, gains a thousand-fold in beauty when you, as it were, soil it with a black tint, while all other light stones, as soon as you touch them with a tint, lose their splendour, and turn black; forsooth this is owing to some occult power, some secret of nature in the diamond, which human imagination cannot penetrate. There are certain sapphires, which the ingenuity of man can turn white, by putting them in a crucible in which gold is to be melted,[49] and if not at the first heating, then at the second or third. Indeed your cunning gem-setter will always pick the palest sapphires, because, though they have the least colour, they are the hardest in substance. The same holds good of topazes, which are of similar hardness to sapphires, & so may be classified with them. I propose here only to touch on these two stones in so far as they have kindred qualities to the diamond. There are few, then, however great their experience, when having before them the two stones could tell which of the two was the diamond, often being unable to distinguish them at first sight. The peculiar virtue of the diamond, however, admits of the trying of a simple experiment, by which you can at once distinguish one stone from another, and it is this. You take your tint & rub both stones with it; your true diamond grows in brilliance & beauty, the other becomes deadened and splendourless. And this test suffices without trying the test of hardness too, but if you rubbed the two stones together you would soon find out the diamond. Though the sapphire is so much harder than the ruby & the emerald, it is a thousand times less so than the diamond. By the way, I need hardly mention that it would be absurd to test a polished gem by the above method. That’s as much as I want to say about the diamond.
FOOTNOTES:
[46] Specchietto.
[47] This diagram may be taken to illustrate Cellini’s description:
Diagram illustrating the specchietto for the diamond
D. Diamond.
A. Reflector.
B. Bezel tinted inside.
[48] Citrini.
[49] Nel quale sia dell’oro che s’abbia a struggere.
CHAPTER XI. ABOUT WHITE RUBIES AND CARBUNCLES.
I promised to tell you something about the finest sort of rubies, but before doing this, I want you to know something about another sort of ruby, called the white ruby. This stone is white by nature, not by any heating process like the other stones mentioned above, & its whiteness may be likened to the chalcedony, the twin sister of the cornelian. The latter has a sort of unpleasing livid pallor, & for this reason is not used much.