clasp and authenticity of pearl necklace

I have an offer to buy a cultured strand of cream colored pearls but there is no paperwork. The clasp is gold colored with 'G.Silver' stamped on the bottom of the clasp and Pat.P stamped on the clasp's hoop.

Thats all the markings. The pearls are individually knotted and approx 12 inches in length (when closed). They are asking 200 dollars at a reputable resale shop.
Does the clasp provide any clues?
Thanks!
Ginny in CO