Robert Fletcher Always referred to this device as the Bio Buckle and in joking the "Belly Warmer"...It was for all purposes an excellent Idea at the time..a device worn by all Starfleet personnel to monitor the wearers Bio functions...Beyond popular speculations this was never ever referred to as the "Perscan" device amongst the production crews and developers...OIt was Fan made up like the extra large captains shoulder rank in TWOK or the Fleet Captain rank...These were made of resin and there were several different paint schemes...The original I owned was a gloss black...This was in the early eighties...Speculation is that they were black with a dark brown outer base..I have NO basis as I do not own mine anymore but a gloss black does sort of answer the question..Reflection..If your wearing a tan suit the rim will look brown from the reflection as well as grey/blue...I can only go by what I owned and what Fletcher told me..The pictures below are from the It's a Wrap auctions..But to be honest..Gloss black or brown highlight, both are accurate..enjoy
notice the blue highlights
Has a black look too it
In different lighting against the Tan