I wondered that too... I had found a ring that I thought was costume jewelry until I relaized it had a stamp on the inside of the band with that same thing. A place on eBay is selling a ring and this...
The numbers on rings are super tiny so what you are probably reading is either 42.5 or 92.5. If the ring is gold you are seeing 42.5 which means that the ring is 42.5% gold and the rest alloy. If the...