The topaz is mentioned in the Bible as the ninth foundation stone of the New Jerusalem. It has not entered greatly into literature, being an undramatic stone, and is not usually at its best when combined with others; but it can be so fashioned as to display a serene and quiet beauty.
Tourmaline
The tourmaline is any of a variety of complex silicoborates, formed into a brittle mineral, crystalline stone. It was originally found in Ceylon, first being brought to the West in the eighteenth century. The surface of the stone has a vitreous lustre. A black, opaque variety is called schorl; a blue variety, indicolite; a red, rubellite. The tourmaline is most attractive, and most frequently chosen for jewels, in a colorless transparent or translucent variety, and in deep green.
Turquoise
The turquoise was originally found in Persia, where it is still a favorite and lucky stone. It was also found along the Sinai Peninsula; but it was transported to the West by way of Turkey, whence its name, the Turkish stone. It is also found in the western United States and, in its rare crystalline form, in Virginia.
The turquoise is a hydrous phosphate of aluminum, with a little copper or iron determining its color, from sky blue to greenish grey. It is best when a rich green-blue. The stone is rather soft and is cut cabochon. Like the opal, it absorbs grease and dirt and may grow dull. Over-exposure to strong light will cause it to fade.
There may often be several hues in the one turquoise; it is another stone that can be wrought into parures of quiet beauty.
Zircon
Zircon is really a silicate of zirconium, an element discovered by Martin Klaproth. Zircon is chemically Zr Si O₄, a mineral occurring in tetragonal crystals. Though it is found in many colors—yellow, brown, red, pastels of green and blue—the colorless and transparent varieties are in demand for jewels. The brown zircon, heated, turns first blue, then colorless. Without the diamond hardness and full sparkle, the colorless zircon more nearly approaches the radiance of the diamond than any other stone.