Smaller mined vs bigger lab diamond?

I'm a bit torn on what to get for my partner. I know that she is particular about size. (She doesn't want gigantic, but substantiable on her size 5.5 hand) But we have not discussed whether or not she preferred natural or lab. I don't want to ask her further questions either because I want to keep it a secret.

I guess most of you guys would probably say that I will know her better and I will know the answer myself. But keen on feedback nonetheless.

I am planning on a 0.96 carat mined diamond but having second thoughts maybe getting a bigger lab diamond.