The Black Enforcement

The Black Enforcement was a secret police enforcing Homeworld law during late Era 2 and early to mid Era 3. They were comprised up nearly entirely of Neptunites and were highly disliked by all the gems who knew about their organization.

Role
The Enforcements were given orders by high ranking gems like Emeralds or Plutoniums, or even White Diamond herself, to find and eliminate particularly troublesome gems. This ranged from dispatching rebel leaders to fleeing groups of gems.

Controversy
To be expected, rebellious gems and the Crystal Gems highly disliked the Enforcement, calling them Breakers as a show of disdain. However, due to the secretive nature of the organization, many gems simply didn't know of their existence. Pink Diamond, as Rose Quartz, told her closest allies about the group, as she was one of the ones to make the cut of gem. Higher ranking Homeworld gems would refer to the gems within the Enforcement as "Voids". Due to the nature of their job, as a Void you have enemies everywhere.

Neptunite
An ex-Void, Neptunite was one of the first members when the Enforcement was created. He worked his way up the ranks until he had his own team, consisted of non-Neptunites, something rare within the group. They were all notable warriors, however as the centuries after the start of the Crystal Gem rebellion, one by one they were shattered. After his last teammate was brutally tortured and shattered by the rebel leader Fluorite, he left the Enforcement and the Empire, returning to Earth after the start of Era 3.