Richard- Excellent post. I just have a couple of quick additions....
The burnishing procedure is risky
You are so right about having a well polished point to burnish with.
The only thing I add is spit for a lubricant.
On larger faceted stones over a couple of carats I like a heavier
bezel and so it's important to slightly bevel the top outside edge a
little to help it move over the stone. Often we use a 1/2 onglette to
tidy up the inside edge. In that case we do go in both directions to
smooth out any bumps and then use the burnisher. Again careful
control and a lubricant is important. If it's a scary soft stone I'll
do that when the bezel is 90% of the way down and then take it down
the rest of the way.
I personally have more control over a hammer and a chasing tool than
a rocker or burnisher. But then I'm a hammer girl by nature and feel
most comfortable with one. I was a liturgical silversmith for a few
years so a hammer is most comfortable for me.
We start our students out with a ton of cheap CZs and silver so that
they can test their limits without a huge expense.
It's all about practice practice practice and what works best for