Them being a tracking device doesn't make sense.
The diamonds know nothing about the breakout. If they were trackers, then the worst I could see is Holly showing up herself to get him back.
Holly Blue would never tell TWO FUCKING DIAMONDS that she fucked up and let the newest humans escape with a group of rogue gems.
That's the point Pearl made at the end of the episode.
Holly's getting her ass pounded by Quartz dick for the rest of her life because that at least beats getting shattered.