Regarding DiamondBlades, I found this passage on their site while reading about what makes a good knife (which I can understand is their objective):
"Thus another measure of a high performance blade is one that has a softer tough spine and a very hard edge that is not so brittle as to chip in normal use."

Well, here is the problem and the information which says they are not competing in the area of toughness and hard use knives. I do not consider a knife is tough if it doesn't chip in normal use! And it's also important what each knife manufacturer understands by "normal use". I have used a lot of steels. I have the Fallkniven A2 which's edge at 59 HRC chips while hitting rocks (it chips like glass). And I don't like it because of that! It doesn't chip in normal use. It also doesn't chip while chopping in normal wood. But hitting something harder chips it like glass having pieces of it jumping out of the blade. I suppose diamond blades are excelent knives for normal use. But when talking about the toughest knives in history we are actually talking about more than normal use. Until now, from what is available to buy with money, I only found few blades made nowdays which can hit rocks without chipping (however, they still took some kind of chipping, but which had the shape of the target, so I admit it was more local deforming than glass-like chip). These blades are the Bussekin blades, the SK5 steel blades from Cold Steel and maybe few other blades, but which do not have good edge retention. The SK5 is also inferior in RC hardness (being around 54 compared with INFI at 58-60). So, I keep up my opinion that the technology advantage today is more oriented to improve normal use performance rather than toughness.