Vintage Costume Cameo Necklace and Earring Set - Cannot interpret mark

Beautiful colors used for this set. This is another piece that my eldest daughter selected from my Mom and Grandmother's collection. Due to the fact that the earrings are clip on, this probably belonged to my Grandmother.

I found what looks to be a mark but cannot interpret it. It looks like a "P" followed by a 'Crown" and then 2 more letters??

I have pics of the mark in 2 different lighting situations.

Any helps with identifying this is most welcome!