Have you tried Rail Revolve followed by Shell?

Martin.

Hey Martin, thank you, that worked!
Gunter

Hi Gunter

A different method to make it more organic is this.
Using 2 profiles top and bottom, 2 sweep rails and outside scaling rail
if you show the oval profile around the stone and the cutting plane you can adjust the scaling rail points and top profile so you match it.
Then cut the top off to get your oval and boolean out stone holes
boolean out the inside to give you a flat.

all done
cheers
shayne

@shayno - this is brilliant, thank you SO much!