CONSIDERED IN THEIR SCIENTIFIC AND ARTISTIC RELATIONS.
DEFINITION OF PRECIOUS STONES.
Beauty, durability, and rarity—such are the qualities characterising the minerals to which we apply the adjective "precious." But the term "mineral," though including all true precious stones, does not exclude some natural products of the earth (such as gold and platinum) which, though precious, are not stones in the ordinary acceptation of that word. Native metals, then, are outside the category of precious stones. On the other hand, at least one animal product, the pearl, is commonly ranked with such minerals as the diamond and the sapphire, associated as it is with these stones in jewellery, and partaking as it does of the characters of beauty and rarity, with a good share of durability.
After all, it is no easy matter to define a precious stone. Where can the line be drawn between stones that are precious and stones that do not merit that appellation? Is not the preciousness of one sort of stone or of another dependent in part upon caprice, upon time and place? If the fashion follow some new direction, then gem-stones now reckoned of small value might in some measure displace the diamond and the ruby; for, compared