Gems can be slotted into weapons with the appropriate slots. They can be acquired from chests (3 locks) or randomly - with a low chance - from the mining machine.
Currently gems are only cosmetic. It is planned for a future update that they will give bonuses, but specifics are - as of yet - unknown.
There are 3 shapes and 3 colors of gems currently in the game.
Not every blade has slots for every shape of gem. The first one that can hold any gem at all is the Short Sword, which can hold two round gems in its pommel.
|Blade||Round gem slots||Square gem slots||Triangle gem slots|
|more to come||...||...||...|