The Green Sapphire is a gem added by both RedPower 2 and GregTech 5. Its main purpose is to craft tools. It generates between the Y-levels of 0 to 48. It can be pulverized and macerated.
Green Sapphire tools are the tier between Iron and Diamond. While they have the speed of Diamond tools, they only have 501 uses and Green Sapphire pickaxes cannot mine Obsidian.
Green Sapphires can occasionally be found in Dungeon chests.
Green Sapphires can be used to craft the basic tools, Saws and Sickles. A Green Sapphire is also required to craft the Sonic Screwdriver.