I've seen a picture showing how to spot female seeds, being said to be 100% sure.
You may find that on google by "Identify male seed cannabis".
Nice to see a male run here!! Such a rare thing! Good luck choosing your plants!! And why did you choose diesel?
And if it is and its your only plant leave it till sacks will open up. Vollect polen into plastic bag and freeze it. You'll have free seeds later , when you will have a girl ;)