A Blue Diamond has no stress bars and cannot display stress in this way. Cobalts which predate Blue Diamonds by about 15-20 years and first bred by Jack Wattley have stress bars and they will show when stressed, sick, etc.
I think this answers the question if I understand what you're trying to get at. Under optimum conditions they resemble each other, no stress bars, outside of that they are two entirely different strains.