Hi Olga,

The easiest way to cut the cone out of the ring top is to first make sure you're working with closed objects.

In your model, the end point of the construction curve on the side didn't connect to the ellipse on top, causing the
network surface to not conform to the curves, which would cause some problems connecting
the bezel surfaces to to the ring as a closed "leak-tight" model.

And as Burr mentioned, hiding the object in the way will let you pick the cone. But I guess old habits die hard.. :-)
I also capped the cone before I subtracted it from the ring, which is the way you'd have to do it in Rhino.


-Jesse