A Half of a key is a rare item drop which may be received from any monster that drops gems. Using the "teeth" half on the "loop" half or vice-versa will create a crystal key. Using said key on the Crystal chest in Taverley will give the player several rare items. The chest has a 100% chance of giving an uncut dragonstone, as well as the possibility of various other items, such as coins, runes, and rune bars.