Hardness 8, Specific gravity 3.5-3.6, Reflective index 1.6-1.64

Topaz has low dispersion and a cleavage perfect in one direction. Topaz is recommended for those whose solar sign is Gemini. It can also be worn by those under the signs of Libra and Scorpio.

Topazes can be orange-yellow, amber-gold, blue, purple, the color of sherry, brown, or pink. The most valuable topaz is known as Imperial topaz, and it is reddish gold. The pink and peach (brownish yellow) topazes are more costly than other colors. Blue topaz is the most common and the least expensive. Blue topaz comes mainly from China. It is colorless or white when it is mined, but irradiation changes the stone to an electric blue. If this is done improperly, the gem can become radioactive, and it is not recommended for astrological use when irradiated. Other topazes are found in Brazil, Russia, Ukraine, and Pakistan.

Topaz is a hard gem, but it cleaves easily, so a hard blow can crack it. A sudden change in temperature can also cause topaz to crack.

Topaz can have a good influence over the mind and soul. It helps one become more aware, happier, creative, improve one's concentration, increases one's intelligence, and helps one have better clarity of mind. It helps improve wealth, relieves depression, and helps one avoid misfortune. Topaz can help those with dangerous jobs, and can help make life more pleasant. It also helps a couple remain loyal to one another.Topaz works with the nervous system, relieves exhaustion, mental problems, and diseases of the solar plexus. It can help cure heart complications, migraines, liver problems, diarrhea, rheumatism, ulcers, insomnia, arthritis, jaundice, impotency, and gout.