yes, it took me a while to see it since I don't see that well up close. Had to use a magnifying glass lol It say "25" in a sunken square. And then the initials P D stamped into it. Not sure what it means. I bought it new so I know it's no ones initials. But I bought it in the 90's & can't remember where.
It has never turned my finger green any time I wore it. I have never worn it all the time. Just for special occasions. I think it looks like black onyx but I don't think it really is.
well, I just googled it and what I got...• PD (noun)
PD Meaning: A silver-white metallic element of the platinum group that resembles platinum; occurs in some copper and nickel ores; does not tarnish at ordinary temperatures and is used (alloyed with gold) in jewelry.
I think the 25 is what percentage. I hope that helps :)