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Topaz is a precious stone. Pure topaz is colorless and transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow, pale gray, or pink. They may be made white, gray, green, blue, pink or reddish-yellow and transparent or translucent. The name "topaz" is derived from the Greek TOPASIOS, the author of one of the first systematic treatises on minerals and gemstones dedicated two chapters on the topic in 1652. In the Middle Ages the name Topaz was used to refer to any yellow gemstone.

Topaz may be found with fluorite and cassiterite. It can be found in the Ural and Ilmen mountains (Russia), Afghanistan, Sri Lanka, Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico, Flinders Island and the United States. Some clear topaz crystals from Brazilian pegmatites can reach boulder size and weigh hundreds of pounds. Crystals of this size may be seen in museum collections.

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The famous Braganza diamond is in most likelihood a topaz. The topaz of Aurungzebe, observed by Jean Baptiste Tavernier measured 157.75 carats. Colorless and light-blue varieties of topaz are found in Mason County, Texas, but there is no commercial mining of topaz in that area.

Blue topaz is a December birthstone, like turquoise. It is the Texas state gemstone, often cut with the Lone Star cut - the Texas state gemstone cut showing a star in the heart of the gem. The Texas Natural Science Center exhibits a 1778 carat blue topaz found in a Brazilian mine. Topaz very rarely occurs blue naturally. Typically, colorless, gray or pale yellow material is heat treated and irradiated in order to turn it blue. There are are several varieties of blue topaz common to the jewelry industry:

• Sky blue topaz, often simply called "blue topaz", it is the most common seen in jewelry. Its color is fairly similar to that of top-quality aquamarine, but without aquamarine's gray components. Its also available in a wide range of sizes.
• Swiss blue topaz, which has a electric blue appearance. It has a more saturated color than sky blue topaz.
• London blue topaz, which is a deep steely grayish blue color. It is the darkest non-coated variety available on the market. Its name does not imply its origin.