It was revealed to be a communicator in "Message Received", offering direct contact to any member of the Great Diamond Authority through the Diamond line. It was destroyed in the same episode by Yellow Diamond through its remote detonation feature.
The Diamond Communicator is an octahedral object with the facets colored white, light yellow, light blue, and light pink with each color representing an individual Diamond member.
To be activated, the communicator must be twisted 180°. After selecting a color, it will then send a signal to the chosen Diamond and project a screen, allowing the user to communicate directly with them.
Steven, having noticed that Peridot stole it, takes it from her and threatens to destroy it if she doesn't tell him what it is. She reveals it to be a communicator that can be used to contact any of the Diamonds. Later on, Peridot makes contact with Yellow Diamond through the device. Peridot terminates her allegiance to her after an argument and cuts off the communication. Yellow Diamond responds by detonating the communicator remotely, but it was bubbled by Steven and knocked away by Garnet before the blast could hurt anybody.
When the Ruby Squad is on the Moon Base with the Crystal Gems, Doc notices that the communicator is gone and the panel is smashed thanks to the events of the Gems' previous visit. This prevents them from contacting Yellow Diamond, to the Rubies' frustration.
It is shown at Pink Diamond's Garden during Steven's broadcast in Era 3 witnessed by Spinel, and in flashback, Blue and Yellow gave Pink for her own first colony: the planet Earth. After Spinel got her memories back, she destroyed it.
- It can be assumed that the Diamond Communicator's use is reserved solely for the Diamonds or at least high ranking gems because Yellow Pearl referred to it as the "Direct Diamond Communication Channel"
- The communicator's signal is extremely strong as the transmission can travel across beyond the moon all the way to Homeworld.
- The Diamond Communicator can be remotely detonated and cause a potent explosion, as shown in "Message Received".
- The base in "Jungle Moon" has no sign of a Diamond Communicator.