Danburite is a crystalline mineral similar to topaz. Its chemical formula is CaB2(SiO2)2. It has a Mohs hardness of 7 to 7.5 and a specific gravity of 3.0. The mineral has an orthorhombic crystal form. It is usually colourless, like quartz, but can be also either pale yellow, yellowish-brown, or pink. It typically occurs in contact metamorphic rocks.

It is named for Danbury, Connecticut, United States where it was first discovered in 1839 by Charles Upham Shephard.

Reference: Wikipedia

Danburite is white and bright, clean and clear—all the attributes you associate with diamond. Yet no one would mistake it for the king of gems. Hey, you want a natural gem that people would swear is diamond, try white sapphire or colorless topaz.Danburite gives jewelers the chance to create a big, white, classic look—elegance that can be worn with anything. It is $20 per carat—one tenth the current rising cost of increasingly scarce white sapphire.Of course, with a hardness of 7, as opposed to sapphire’s Moh’s scale rating of 9, danburite probably shouldn’t be equal in value to corundum. A 7 rating for danburite sends hands-off signals for ring use—or, at least, everyday ring use. Aware of the gem’s borderline suitability for rings, The Gem Vault’s designers restrict danburite mostly to earrings or pendants. But white on the ear or on the neck is just as noticeable and nice as white on a finger. Danburite is untreated and it is rare—two wonderful strengths on which to build a reputation.Today, all colorless danburite comes from Mexico. Sizes range up to 10 carats, although some behemoths make it to market.

Reference: Modern Jeweler