LONDON - FILE PHOTO MID-1980'S: The Queen Mother at an evening engagement wearing the ring given to Camilla Parker-Bowles as an engagement ring. The necklace had been a gift to Princess Alexandra of Denmark from her future husband the Prince of Wales and worn on their wedding day in 1863. (Photo by Tim Graham/Getty Images)

LONDON -  FILE PHOTO MID-1980'S: The Queen Mother at an evening engagement wearing the ring given to Camilla Parker-Bowles as an engagement ring.  The necklace had been a gift to Princess Alexandra of Denmark from her future husband the Prince of Wales and worn on their wedding day in 1863.  (Photo by Tim Graham/Getty Images)