Maybe this is a semi-royal topic. Two threads below set me thinking of jewels copied in paste to be worn in place of the real thing, for safety and insurance purposes.
I do believe that some families have had copies of jewels made to wear in place of the real jewels which sometimes stay safely stashed in the bank vault.
Royalty might not have the same reasons to order copies made. Royalty goes out surrounded by secuirty, and the jewels would be valued mostly beyond the cost of insuring them anyway.