From Mine Blocks Wiki
Topaz is a gem found deep within the Mine Blocks world. It's rate of appearing is 7/10 so it's not the rarest gem. It currently has no use, but in a later version of Mine Blocks, Topaz could be used to trade with villagers.
- The color of topaz in-game has been changed many times. It was originally blue, then changed to yellow. After that it was changed back to blue.
- Although in real life, topaz is transparent, in the game it is blue. This is to avoid confusion with diamonds.
- Topaz in real life can also have an orange color.