Blue Topaz

Color:   Sky blue to a dark medium blue
Gem Family:   Topaz is a gem family that includes the relatively rare precious topaz, the coveted sherry-red to orange imperial topaz, and the delicate pink topaz. However this gem family is most well known for enhanced blue topaz, the most affordable and available of gems.
Source:   Pale topaz which can be enhanced to become blue is found in Brazil, Sri Lanka, Nigeria, and China. The gems are usually cut before they are treated, since the process can be pricey and stones with inclusions may fracture.
Clarity:   Blue topaz should have no visible inclusions
Size Range:   Any size
Shapes Available:   Any shape
Enhancement:   The strong icy blue color of blue topaz is created by exposing colorless topaz to irradiation and heat. Lighter colors are created by electrons and the darker blue known as London or Super blue is created by neutrons. Some gem treaters have secret recipes to create particularly pleasing hues so the exact procedure is often secret. The process can take minutes or years, as high-energy processes require that the topaz is stored before it can be released safely.
Lore & History:   Legend that topaz dispels all enchantment and also helps to improve eyesight. The ancient Greeks believed that it had the power to increase strength and make its wearer invisible in times of emergency. Topaz was also said to change color in the presence of poisoned food or drink. Blue topaz is an alternate birthstone for December.
Toughness & Hardness:   Topaz has a hardness of 8 on the Mohs scale and it is quite durable.
Care & Cleaning:   Topaz is a very hard gemstone but it can be split or "cleaved" with a single blow, a trait it shares with diamond. As a result it should be protected from hard knocks. Clean with mild dish soap: use a toothbrush to scrub behind the stone where dust can collect.
Special Characteristics:   Perhaps the most famous topaz is a giant specimen set in the Portuguese Crown, the Braganza, which was first thought to be a diamond. There is also a beautiful topaz set in the Green Vault in Dresden, one of the world's important gem collections.