The sequence of photo's fully shows how I set a Diamond into a fairly large Bezel frame, I believe this was a 1/4 carat Diamond. The very first thing you should do is grind out the top rim of the Bezel to at least 80% of the circumference of the stone. The balance of 20%, will be remaining INSIDE of the Bezel frame, nicely covered & being made secure! By using your HSS of 45degree (as shown) you should have the teeth start carving out a bearing. The question is how far down into the bezel should the bur be? Exactly to the depth of where the teeth of the bur are not seen anymore in their cutting process, now isn't this simple? Attempt to slide the stone in on a 45-degree angle into bearing seat, this is to avoid any chipping as its being placed straight down!
Now you've gotten the stone sitting in it's seat I would gently remove by filing with a Pillar File of #2 cut and just remove the outer edge. As this is where the reciprocating hammer will be hitting, again on a 45-degree angle. Interesting numbers (45 here and 45 there), you will notice that this is a common number when drilling and filing!
Start your hammering not anywhere near the diamond but just further back, I don't want you to hammer and hit the stone. I could do this if I had an Emerald! If the hammer-anvil is vibrating & not hitting where you need to, it still won't hit the stone, get my drift? Safety at all times, in filing and hammering!!!
When hammering start at the 12:00 clock, then to the 6:00, swing over to the 9:00, then 3:00 oclock. Then just finish all around & fill in the remaining gaps, this sequence is common on all round bezels!
Now you can, once finished, use an Onglette graver #2 & Bright-Cut around the inside of the bezel. How difficult is this setting on my "Difficulty Scale of Setting"? I'd put this on about a 6.5..Just have fun!!!!
When you are totally finished, use your Pumice Wheel @ #180 grit followed by #1,000 Pink Wheels!