NOS? Does it have a label, or does it just look unused? Those "number in diamond" have the characteristics of later Favorites, but could also be Chicago Hardware Foundry, who bought Favorite's patterns and tooling when they went out of business, so they could be the unmarked pieces of either maker. Crust? Could it be enameled, perhaps?
After a brief search, I'm looking at what surely must be the ended auction. Unfortunately, that is not NOS. That's build-up from usage, the whiteness just being how crud sometimes looks. If it's not cracked (I don't see any in the magnified close-ups) or warped, it should clean up easily and be a fine user. It doesn't appear to have been abused, nor does it appear pitted. The selling price, IMO, would be OK if not for having to pay to have it shipped.