I doubt anyone except the vendor upstream knows, and even then, it's unlikely you'd talk to the right person. To compound the issue, you will almost certainly not be able to find out/know the hardness of the cones or races for the system you're putting them in. IMO, hardness (at least as it pertains to bicycles) is not an issue, if you're buying quality (grade 25) bearings. Grade DOES refer to quality, after all. Yes, it doesn't denote hardness specifications, but (again) my experience is that it isn't really necessary to seek out that info for bicycles.