Round is the shape you land on if you do not overthink it, and there is a good reason for that: a round brilliant is cut to throw more light back at you than any other shape, which is most of why it has been the default engagement stone for a hundred years. Classic is not the same as boring. It is the shape that still looks right in a photo ten years on.
Almost all of these are settings, whoever made them. You pick the round design; the center diamond is the separate call we make together after, lab grown or natural, sized to the setting and your budget. A few arrive complete, the stone already set, and those say so.
A setting check comes free once a year with anything bought here, for as long as you own the ring. Round is the shape that never has to be explained to anyone, which is either the least adventurous reason to choose it or the most honest one. Both, probably.