Blue Topaz is both a pretty and a very affordable stone. Naturally occurring blue topaz is quite rare. When mined, the rough material is very pale. Heat treatment enhances the blue color and is permanent. It is not a coating. Heat treating the raw material is standard in the industry. Blue topaz is mined around the world. It is a moderately hard gem with an 8 on the Mohs scale for hardness, making it a perfect stone to wear every day. It is plentyful and available in large sizes. It's also easy to get matching stones.