To me, its a fat pear shape and I treat it much the same way. Start
with the point. There are two reasons for this. One, safety. If you
set the point last you may break the point because the best you can
hope for is to draw the prong JUST down to the stone, too much squish
with the pliers trying to level it and you hear that awful, tiny
Two, flexibility. Set the point first and you can alter the other
seats to suit, giving you more control in leveling the stone. You can
put more coercion to the heal or shoulders than you can to the point.
I should point out that your stone will be in and out a few times
during trial fittings.
Now it just occurs to me that you might mean bezel setting. This is
trickier. Usually at the cleft you have an enormously thick girdle
so getting a true seat is problematic because the girdle extends way
down the pavilion.
You just don’t really need a seat at the cleft. Make whatever
aesthetic accommodation you need to cover the cleft, depending on
whether you have a curved or angular ‘notch’. Try to get a
reasonably tight fit at the point and cleft. These are your anchors.
When rolling over the bezel start at the point and go a few MMs down
each flank. Then start rolling the bezel again but from the cleft.
Work your way alternating from each end toward the fat middle curve.
The principle is the same as with bezeling an oval. If you work to
the ends from the middle (undesirable) you may wind up with a fold or
crease in the bezel because the deformed metal has nowhere to go.