Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/169

 ago this gem was considered to be a variety of diamond; it was usually set in rings, buckles, and around stones of little value: at present it is seldom used in jewellery, and therefore bears but a very low price.

TOURMALINE. Tuts stone is remarkable for its electrical properties. It generally occurs in black and opaque crystals; but the precious varieties are translucent, and of a green, blue, or pink color; they are used for ring-stones, brooches, or seals. By heat or friction it becomes elec tric, and may be distinguished by this property, which it retains many hours.