Emerald

Emerald is a gem found within the Underground and Cavern layers of a world. They are obtained by breaking special blocks that have noticeable green gemstones embedded in it. They can also be extracted from Silt, Slush, or Desert Fossil by putting them in an Extractinator. Rarely, Emeralds can be found in bulk in its own special gemstone cave, or in one that contains all of the other gems as well (besides Amber).

Like all other gems, Emerald can be placed on blocks. As of 1.4.0.1, they can be crafted back into their Stony block forms at a Heavy Work Bench in a graveyard and can be obtained by cutting down an emerald Gem Tree, dropping 0-5 of its respective gems.