Topaz is a silicate mineral of aluminium and fluorine with the chemical formula AlSiO(F,OH). It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden brown to yellow orange. Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple. Although it is often associated with golden yellow and blue, it comes in a variety of colors, including colorless. The rarest are natural pinks, reds, and delicate golden oranges, sometimes with pink hues. Topaz is a nesosilicate mineral. It is one of the hardest naturally occurring minerals and has a relatively low index of refraction. It occurs in many places in the world. Etymology The name "topaz" is usually believed to be derived (via Old French: Topace and Latin: Topazus) from the Greek Τοπάζιος (Topázios) or Τοπάζιον (Topázion), from Τοπαζος. This is the ancient name of St. John's Island in the Red Sea which was difficult to find and from which a yellow stone (now believed to be chrysolite: yellowish olivine) was mined in ancient times. The name topaz was first applied to the mineral now known by that name in 1737. Ancient Sri Lanka (Tamraparni) exported native oriental topazes to Greece and ancient Egypt, which led to the etymologically related names of the island by Alexander Polyhistor (Topazius) and the early Egyptians (Topapwene) – "land of the Topaz". Pliny said that Topazos is a legendary island in the Red Sea and the mineral "topaz" was first mined there. Alternatively, the word topaz may be related to the Sanskrit word तपस् "tapas", meaning "heat" or "fire". History Nicols, the author of one of the first systematic treatises on minerals and gemstones, dedicated two chapters to the topic in 1652. In the Middle Ages, the name topaz was used to refer to any yellow gemstone, but in modern times it denotes only the silicate described above. Many English translations of the Bible, including the King James Version, mention topaz. However, because these translations as topaz all derive from the Septuagint translation topazi[os], which referred to a yellow stone that was not topaz, but probably chrysolite (chrysoberyl or peridot), topaz is likely not meant here. An English superstition also held that topaz cured lunacy. The ancient Romans believed that topaz provided protection from danger