Ruby

Ruby is a gem both added by RedPower 2, Project Red, and GregTech. They are used for tools, Energy Crystals and Mining Lasers. Ruby dust is the main source of Chrome.

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

Rubies can occasionally be found in Dungeon chests.

Usage
Rubies can be used to craft the basic tools, Saws and Sickles