i doubt anyone is going to give you that. how can they certify potency when you do the growing? they dont how much you know about growing right?
so if you dont have the same level of skill as they do how can they "certify" you will get the same results as them.
thats asking way too much. that can however tell you what level THEY can achieve and most will give some kind of idea of POTENTIAL potency, usually under ideal conditions.