Princess May of Teck (later Queen Mary) received a diamond and ruby bracelet set in gold from the County of Cornwall for her 1893 wedding. Her husband, the Duke of York (later George V) also gave her a jeweled diamond rose which she wore as a bracelet, so there is some confusion around this particular piece. Nevertheless, it is referred to as the County of Cornwall Bracelet.
The central rose can detach from the bracelet to be worn as a pendant or a brooch, as seen on Queen Mary’s collar above. She gave the bracelet to her granddaughter Princess Elizabeth in 1947 as a wedding present.
Today, the Queen uses the bracelet occasionally with her other ruby jewels. It’s not a bad accompaniment to the similarly bold and floral Burmese Ruby Tiara. She seems to keep it as a bracelet, not using the brooch option for the center portion.