you can do a spark test on it if you have a grinder... the type of spark it throws relates to carbon content (and therefore whether or not it can be hardened)... if you want to be super accurate get a pmi done.... if you want to pay shipping we have pmi in my shop (I can slip it through) (send a small pc)... but being a stainless, if not a 400 series, you don't hear about a ton in blades... might accidentally be a 17-4 ph...