Caste System

Before Era 3, the Gem Homeworld maintained a strict Caste System with gemstones having predetermined roles, places, privileges and ordained purposes in the social pyramid, and Gems who deviated from this were considered defective. Since penalties were severe, disgruntled Homeworld Gems kept to themselves or went into hiding. Because there were so many of each Gem-type (except Diamonds), all Gems normally distinguished themselves via serial numbers. The Caste System was divided under the rule of the Diamonds and other Homeworld elites; if Gems were to greet or refer to others in higher sections of the Caste System, they normally prefaced their Gem name with "My" to show they were their superior(s).

As of the time between "Change Your Mind" and Steven Universe: The Movie and around Unleash the Light, both it and the Gem Empire had been officially dismantled.

Real-World Relations/Differences

 * Ruby and sapphire are varieties of corundum in the real world while Rubies and Sapphires were different and unrelated in the series, possessing different roles in the hierarchy. The same applied to Aquamarines, Emeralds, Bixbites, Morganites, and Beryls which were all beryl in the real world but separate and different in the series. Nephrite is under jade in the real world but Nephrites and Jades seem to share no technical relations although both were voiced by Aparna Nancherla, possibly as a nod to their real-world equivalents.

The Caste System was somewhat tied to real-world gemology and mineralogy (i.e. Diamonds being the highest as real-life diamond is highest on the Mohs scale of mineral hardness). However, this was not a proper rule for the series as it took creative liberties with Gem-types and their rankings including but not limited to:

(This page needs more things added to it and therefore being unfinished)source