The Sontarans are an alien race who opposed The Doctor in the long-running british television series Doctor Who. The are a small humanoid race with a head often described as looking like a baked potato. They are highly belligerent with seemingly no distinction made between the sontaran army and the sepcies as a whole.
The exact design of the sontaran uniform has chanced over the years but is general composed of a grey or greyish blue suit that covers the whole body and a large hemispherical helmet with 2 large eye slit that obscures their feature.
In the 2 part episode The Sontaran Stratagem / The Poison Sky, 3 individual are shown to be wearing rank insignias in the form of rectangular plaque on their collar with the rest having bare collar. The plaques appear to be made of a rubbery material with the diamonds being of the same colour as the background, making them hard to see in some scene.