I believe this type of loop to be made of brass, as such loops were found in excavations in the beginning of the 20th century but nobody knew what they were or what they were used for. I think that, prior to the imposing and very popular "Black loop" worn through out the second half of the century, this was the type of loop that was in style. The brass probably tarnished easily on skin contact so in time, they certainly realised that it was better to cover it in fabric or braided hair. I believe that their purpuse was the same as in later period, they were used to pull the headdress back in place without screwing the whole arrangement in the event that it sliped off. And believe me, it works very well, I've tried this and loved it. These people were geniuses. I used to have to go dig underneat the coif with my fingers to *try* to pull everything back in place, then the hair would start comming out, fabric would loosen, etc... Pulling the loop really does work like magic!!! So here are afew period exemples of this type of "uncovered loops". In the images below, except for the lady in red at the right in the central image, they are all wearing the loop, even the queen...