Vintage 10k Stamped Psco Size 4 Ring Genuine Stone and Gold. A beautiful, delicate ring. This has been in the family for years. It was resized to a 4 to fit niece. She was 13 when she received it. She is 44 now. A beautiful piece of jewelry. Psco is the hallmark of Plainville stock company. They made valuable Jewelry. Marked 10k means it is 10k. Not Plated.