I would like to see .999 silver stamped on it if possible. Is there a reason that wouldn't be doable?
Because I all ready ordered the stamper. I could get it in engraved but that would add a cost of $6 to each set...
You could let them know a mistake was made and you need the stamper corrected.
In my eyes it's a large oversight and I'd expect people to question why the pure silver item isn't marked as such. If anything you could purchase one of the $10 stamps from etsy/ebay and hammer it in yourself.