Ah, yes The Rockwell hardness test.
When buying chisels and you should look at several of the anticipated brand before purchase. Look at the back top of the blade where it narrows down to the tang. Look for three dimples in the back of the chisel. These dimples are how the Rockwell hardness test is performed. You won't find the dimples on every chisel of a particular manufacturer. If you find the dimples, it says that the manufacturer cares about the quality of the steel in their product. The care about steel quality carries over to their product line.
Or that they test for hardness before the finish grind
A lot of custom knifemakers use the same hardness testers for their blades, but not a single one is going to leave those marks on a finished product. Id argue that if youre seeing the dimples, either A) the company doesnt care enough to do the grinding right, or B) that particular chisel is one that went through the random quality testing but somehow made it back on the production line without going through any finishing operations afterwards.
Also important to note, the rockwell hardness of a steel isnt the only quality worth paying attention to, its just one half of the story. I could knock together a chisel blade hardened to 66rhc, and itd be useless because itd be too brittle. Equally important is the toughness of the steel. Dont just look at the numbers for the hardness if you want quality, pay attention to other things. Edge retention, ease of sharpening and wear resistance are all more important than just the hardness, although the hardness of the steel does help determine the other factors.
Basically, if youre wanting to find great cutting tools, compare the intended use to the steels specifics. O1 is a great all-around steel, it had good toughness, working hardness, edge retention and edge quality. Makes for a fantastic razor-sharp cutting tool. Compare that to something like D2, which is miles above in terms of edge retention and toughness, but is a bear to sharpen and doesnt take as keen an edge. It pays to do the research on these things, beyond just the hardness