18" Strand of Blue/Gray Pearls

Hi, I found this strand of blue/grey/purple pearls at the thrift store. I was on the fence until I borrowed a jeweler's loop and saw the 14K mark and the other mark. The jeweler's mark is either a W or a Crown inside of the diamond stamp.

The strand is 18" long, princess length. The pearls are 6mm and have a few color variations of silver, purple, green, blue. The strand is
nicely knotted and the ends by the clasp have been wound in gold thread. That's all I know about this necklace. Any help with identification of the mark would be greatly appreciated.