Gem

Gems are an advance warlike race of artificially grown soldiers, resembling humanoid females. They cause a lot of issues with the RBS as they are difficult to classify, and most scanners often throw errors, insisting that no Entity is found, only rocks. This is due to the fact they are actually just hard-light energy projections from their core gemstone, which can be found somewhere on the body. There aren’t many on the RBS as most of them don’t seem to be keen on business. For more info: http://steven-universe.wikia.com/wiki/Gems

Gem Types
While all the same species, Gems come in various types, based off the gemstone used to make their core. Each type is designed for a specific purpose but some have been known to defect from their original designation and make their own paths.

Some examples:

Ivory
Gems made from Ivory are designed to manufacter and design weapons and technology for military purposes.

Seraphinite
Gems made from Seraphinite are flight capable soldiers designed for precise, long range combat.

Pearl
Pearl's are made to be servants, and are considered quite lowly, and not really capable of many skilled tasks.

Ruby
Rubies are simple foot soldiers and not usually incredibly intelligent, though they are strong for their small size.