Drilling a hole in a marble countertop for a washbasin

[Fixarjon]

Hello,

I got hold of a piece of furniture with a marble top that is 25mm thick.

I'm going to install an above-counter basin from Svedbergs and a hole needs to be made that is 210mm in diameter.
Does this hole have to be round?

Otherwise, it seems like one could use an angle grinder or a multi-tool with the right blade?

As long as the basin covers the hole, you should be able to make a square hole and then glue the basin to the top and press everything together with the bottom valve, right?

 

[sunqan]

It probably depends on whether you find it aesthetically pleasing?
21cm isn't that big in itself, but if I've calculated correctly, the corners will "stick out" 44 mm from the sink.

I would think it looks terrible anyway

 

[Fixarjon]

The sink is 570*42 so it covers the hole well enough. Of course, if it's not difficult to drill such a hole, I'll do it, but what's the best way to go about it then?