The beryl, whether emerald or aquamarine, is rather brittle. Emeralds are seldom found in river gravels. The material cannot persist in the mountain streams that bring down other and tougher minerals. The extreme beauty and value of the emerald has led to its use in the finest jewels, and the temptation is strong to set it in rings, especially in rings for ladies. If such rings are worn with the care that valuable jewels should receive they will probably last a long time without any more serious damage than the dulling of the sharp edges of the facets around the table. This slight damage can at any time be repaired by a light repolishing of the affected facets. If an emerald is already badly shattered, or as it is called "mossy" in character, it will not be wise to set it in a ring, as a slight shock might complete its fracture. What has been said about emerald applies equally to aquamarine except that the value at stake is much less and the material is usually much freer from cracks. Tourmalines, like emeralds, are brittle, and should be treated accordingly. Here, however, we are dealing with a much less expensive material than emerald, and if a customer desires a tourmaline in a ring mounting, while it will be best to suggest care in wearing it, the loss, in case of breakage, will usually be slight. Kunzite, like all spodumene, has a pronounced cleavage. It should therefore be used in brooches, pendants, and such jewels, rather than in rings. Lapidaries dislike to cut it under some conditions because of its fragility. QUARTZ GEMS. Coming down to hardness 7 we have the various quartz gems and jade (variety jadeite). The principal quartz gems are, of course, amethyst and citrine quartz (the stone that is almost universally called topaz in the trade). As crystalline quartz is fairly tough and lacks any pronounced cleavage, and as it is as hard as anything it is likely to meet with in use, it is a durable stone in rings or in other mountings. In the course of time the sharp edges will wear dull from friction with objects carrying common dust, which is largely composed of powdered quartz itself, and which therefore gradually dulls a quartz gem. Old amethysts or "topazes" that have been long in use in rings show this dulling. There is, however, little danger of fracture with amethyst or "topaz" unless the blow is severe and then any stone might yield.