Sapphire

Sapphire is a gem both added by RedPower 2 and GregTech. Their main purpose is to craft tools and Lapotron Crystals.

Sapphire tools are the tier between Iron and Diamond. While they have the speed of diamond, they only have 501 uses, and Sapphire pickaxes can't mine Obsidian.

Sapphires can occasionally be found in Dungeon chests.