Graduation Pearls

In 1968 I received a matinee length strand of cultured pearls for High School Graduation. They were purchased for about $100 at Claude S Bennett, a fine Jewelry Store Atlanta. The pearls were round and well matched.

The pearls have been stolen and I hope to replace them but I'm not sure what type pearls they must have been. Are you able to offer an opinion based on this limited info?