Thomas:
That was one of the best, most thorough answers to a jewelry question I've seen. A few years ago, I was doing a promotion in a jewelry store when a (very angry) customer stormed in, demanding a full refund for a ring she had purchased from the "Estate" department there about a month earlier. The owner had gone out to lunch, and the person who had been left in charge had only been in the trade for a few years, and did not know anything about the subject (The customer insisted that the ring, purchased as 18kt, was bogus), and was not able to handle the irate customer, so he called me over to assist.
As soon as I saw it, I knew who the manufacturer was, as the style (during the time that the ring was made) was very distinctive. Inside the shank was an "18K-P" stamp. (This manufacturer made primarily 18K rings that were of of very fine quality.) I asked the customer why it was that she thought the piece was "fake", and she said that while she was in another jewelry store, someone had offered to clean her ring at no charge, and when she asked about the meaning of the "-P" suffix on the the stamp, she was told that it meant PLATED!
I'll tell you, I generally manage to maintain a fairly businesslike demeanor while on the sales floor of a retail store, but I just cracked up.... it was one of the absolute dumbest things I've ever heard of a someone in a jewelry store telling a customer, and the store she had been in is part of a small family-owned chain with an outstanding reputation and a long lineage. Fortunately, I was able to explain the meaning of the stamp to the customer's satisfaction, and all was well.... in fact, she had purchased the ring at a truly great price.
.... does anyone know what this mark stands for? The ring has a gold band and the setting that holds the "diamonds" is a silver tone. I wear this ring often and it does not leave tarnish marks .