I wondered if some images might help identify the bracelet. In this detail taken from the Beaton portrait the domed shape LDMJ identified seems clear.
Another detail from a different photo. In this image the bracelet appears flat to me.
As HM was wearing blue gloves that may possibly have influenced our perception of colour. Below is a detail from an Alamy photo showing the bracelet against HM's skin.
I am inclined to think that the small dark areas on the above photo are shadows and that there are possibly only a couple of coloured gemstones.