If Your male proves to be a 100% het then any offspring You produced from breeding him to a Normal are 50% het Hypo...If he doesn't prove any offspring produced aren't carrying the Hypo gene.

Until You prove him they are basically Normal Pastels...If You sell any You can disclose they were produced from a poss. het Hypo that You haven't proved.

Your quickest route to proving him is breeding him to an actual Hypo...Even if he isn't a het all the offspring from this breeding will be 100% hets.