Congratulations! You have found a White (Colorless) Topaz gemstone!
Pure topaz, like pure corundum, is transparent and colorless. The wide range of topaz colors you see in the market is usually a result of enhancements by the gemstone industry. Topaz can be found in colors including yellow, orange, brown, red, blue, pink, red, violet and green.
Colorless topaz is fairly common and is sometimes given a brilliant cut and sold as a substitute for diamond. Indeed, one of the most famous topaz in the world is a colorless topaz that was originally thought to be a diamond. It is a 1,680 carat stone known as the Braganza Diamond, owned by the royal family of Portugal. The gem apparently disappeared after the death of King John VI in 1826.
Topaz is a very hard material --8 on the Mohs hardnes scale. While topaz is very hard, it is not the most durable gemstone. That's because it has perfect cleavage, a property it shares with diamond. That means it can be chipped or split by a sharp blow, so it should be protected from hard knocks.