All my blades are hardened and tempered according to the steelmaker's instructions.
Blades in carbon steel I harden myself with gas flame or in a gasesse.
Stainless steel blades I send on hardening, as they must be hardened at temperatures I can not handle myself.
Once the blades are hardened and tempered, I measure the hardness of the steel. Usually the hardness is around 59-61 HRC Rockwell.
I measure the hardness with a Limit 4600 Hardness Tester.