This beautiful necklace was first worn by Camilla in public on 14th November, 1998 in Highgrove, for Prince Charles' 50th birthday - so years before she married Prince Charles. There were rumours about the necklace being a jewel from Alice Keppel, but this is only speculation so far.
On 14th November, 1998 in Highgrove, for Prince Charles' 50th birthday:
On 11th July, 2002, in London, at a society party at Somerset House (fundraising event for the charity ARK - Absolute Return for Kids - and the Somerset House Education Programme):