Topaz is a very common gemstone which has been used for centuries in the craftsmanship of jewelry, and more recently in innovative fashion jewelry . Its blue or golden brown to yellow color is beautiful but is frequently confused with the less valuable citrine, which is sometimes sold under the name topaz.

The structure of the gem is controlled by a chain like structure of connected irregular octahedrons. These octahedrons have aluminum in the middle surrounded by four oxygens. Above and below the aluminum are the hydroxide or fluoride ions. The chains of octahedrons are held together in place by individual silicate tetrahedrons but it is the octahedron chains that give topaz its neat crystalline shape
Topaz is actually the hardest silicate mineral and one of the hardest minerals in nature. However it has a perfect cleavage which is perpendicular to the chains and is caused by planes which break the weaker Al-O, Al-OH and Al-F bonds. None of the stronger Si-O bonds can cross these planes.
Topaz crystals can reach the incredible size of several hundred pounds. It has been known for at least 2000 years and is one of the gemstones which form the foundations of the twelve gates to the Holy City of the New Jerusalem in Israel. These so-called apocalyptic stones are meant to serve in protection against enemies and as a symbol of beauty and splendor.

In the 18th century, it was mined in Germany during a period of over 60 years. However, most of the crystals were hardly even a centimeter in diameter. You had to go to Siberia or Brazil to find crystals which were at least as large as your fist.
Anyone who is interested can convince himself of the beauty of cut specimens in the topaz set in Dresden's Grnes Gewlbe (Green Vault). The enormous and magnificent topaz from the Portuguese crown, the Braganza, was for a long time thought to be a diamond.
In the Empire the topaz was commonly found, but then the more reasonably priced citrine took over from it and even usurped its name - gold topaz. Since then, the topaz has been a rather exotic figure in the jewelry trade, and it has even been given the additional predicate 'pure' to make it clear that the topaz, not the quartz topaz, is intended.