Looking for some advice for doing a waterfall island.

I put a straight line in each of the red circle in the picture below -- the thickness of how the waterfall island or the countertop looks (the thickness of the edge, not the stone itself)

• In this picture, the counter top looks thin, while the waterfall island looks thick (which adds a dramatic look and it is very pretty).
• For my kitchen, we are thinking about 4cm edge for the countertop, and 6cm edge for the waterfall island. Would that be odd? I am just wondering whether the two should be the same edge thickness, unless there is a drastic difference like what is in this beautiful picture below. 4cm and 6cm might be too close and make it odd to be different?
• Also, that would make the countertop 2cm lower then the island (because the base cabinets have the same height). Would that also be bad visually?
• Can you make a 4cm edge with a 3cm thickness quartz, or it has to be a 2cm stone?

Thanks for any comments / ideas.