Jewelry stampings, P4SR stamp, what does it mean?
This and other odd stampings in American jewelry are non-traditional weird mixes of metals which enable the manufacture of what looks like gold or platinum metal, but with a unproven much less valuable metal mixture. I say unproven because there is no track record to see if it can be repaired and/or worked with, if it is color stable, or chemically reactive (will it last or corrode or discolor). The mixtures were not publicized, and many are still held secret. This does not add any confidence to the reason for the creation of the metal, other than to mislead consumers about the value of what they are purchasing. So far most mixtures have a pathetically low percent of gold or platinum. P4SR for example is 1 to 3% gold or platinum plus or minus a pinch and 80% silver with a couple of other cheap metals added into the brew. In America gold is usually stamped 10k (41.7% pure gold), 14k (58.5%), 18k (75% pure), whereas platinum is either 950 (95% pure) or 900 (90% pure) and sterling silver is stamped 925 (92.5% pure silver). All other unusual stamps and stamps with the k in the wrong position, or stamps inside a box, etc. should be suspect if made or sold in North America.