I would lead here. Having nut diamonds is great the Ad5d allows for all combos of Qdd and lower flush combos.

He may have some kind of KKxx AKxx QJTx type hands that continue ideally with diamonds so he can sometimes raise a flop lead but will call and be realistically unable to fold diamond turns as we are repping quite narrow in a 3b pot.

Most likely this will be a you bet they fold scenario, but generally it is imo always better to bet your hands especially when out of position. Aim to be able to get stacks in with a nut hand and a nut draw. This doesnt happen by checking very often.

If you check it looks really suspicious imo. I don't think he is bluffing on the flop, so to get him to bluff would require slowplaying on the turn also. And then you have the risk of missing all the value.

If he misses the board, I don't think you get value no matter what you do. But if he hits it, you get it by betting. So just make the cbet, and make it smallish. Make it look like you might have a weak hand but you want to represent Aces with as low cost as possible.

HU 3betting range will be much wider. So as kyyberi said I would also just cbet smaller and hope he has something.

Im all for cbeting too!

I lost a buy-in this hand