Colorless quartz or pure rock-crystal is found in many parts of the
world, notably in Switzerland, Dauphiny, Piedmont, the Carrara quarries
in Italy, Canada; in Herkimer County, New York, and on the shores of
Lake George, in the same place; at Hot Springs, Arkansas; and along the
beach of Long Branch, Cape May, and many other places.
Rock-crystal, commercially known as Bohemian diamond, occidental
diamond, Lake George diamond, rhinestone, pebble, etc., etc., is
colorless and transparent. This stone is largely used for optical
purposes, and is also sometimes cut into brilliants to imitate the
diamond.
While rock-crystal is considerably harder than strass or paste, it
lacks, however, the brilliancy of the fine-composition imitation
diamond.
Besides being much softer, the paste is often heavier than the crystal,
because of the quantity of lead and other minerals used in its
composition.