the importance of durability, which must claim the second place; and the desirability of a certain degree of rarity, especially where the quality of durability may not exist in the highest degree. How far a very beautiful and hard mineral would maintain its position as a precious stone in the event of its becoming exceedingly abundant, one cannot venture to judge; but as we have to deal with existing facts only, the problem is one which practically has not yet been presented for solution.
As precious stones have just to be looked at and worn, or used in decorative work, it will be readily understood why no occult property is of much moment in determining their value. Individual and learned amateurs may indeed value a stone according to what they know of its history, its romance, its memories, or the curiousness of its components; but in ninety-nine cases in a hundred any enhancement of value through such causes is out of the question. Still, from the mineralogical and chemical points of view, it is perhaps legitimate to import some elements of interest when appraising the right of a stone to be called precious, or its place in the list of gems. One need not follow those writers who speak of precious, semi-precious, and common stones; but one may reasonably arrange the different kinds in a few groups or classes, according to what we may call the average sum of their merits. To assign a precise place to each species is not possible. Hence the futility of such a classification as that published in 1860 by K. E. Kluge wherein emerald takes lower rank than zircon, and precious opal comes after garnet, while to turquoise is assigned a place beneath nine other stones only one of which (peridot) is even known to dealers in precious stones, and to the purchasers of jewels.
