I have some bars of tool steel, 1" round, that the labels have come off. Some are H13, the rest S1. Any method of telling the difference using only regular workshop equipment?

Thanks Stewart, tested and what I think is the H13 showed medium length yellow streaks with a single spark at the end. The other sample showed shorter, redish streaks with a small spark at the end. I wonder if it might be S7. It also sounds distinctly harder on the grinder wheel ( how can it sound hard??? ).