There are many times during the process of setting a center diamond, that certain rules need/must apply. One of the most interesting rules that I came across in my earlier years was this. If the stone had a misaligned off-set girdle (in those earlier days, it did happen!)…Always have the ‘table’ sit flat!! Even when you’re setting a Genuine-Gemstone, this could still happen!
Next, always make darn sure your “Culet” is in the center of the 4-6 claw/prong head! Nothing as so disconcerting as an offset “Culet”!!! My third ruling is; having your ‘bearing-cuts’ accurately proportioned (see diagram). Always have the outer claw/prong that is touching a person’s finger be totally smoothed. Do you want anyone to cut their clothing?
After you complete the bearing-cutting, You will 100% find a little “piece of metal” being extruded only on one side of the claw…this is so very ‘normal’. There are a few ways in removing it.
Simply, GET RID OF IT…NOW! Here are a few interesting techniques, Use your #180 grit Pumice Wheel on that one side where it appears, due to the rotating HSS bur, I use a Flat #40 graver & cut-down from the bearing cut to where the piece of metal is still seen. You ‘could’ use a Triangular #4-cut file, but it will leave little file-marks…:>( Don’t polish it, as the claws will get rounded off…another bad idea!..:>(
I prefer the Flat #40 Graver as the ‘best’ idea, why so? It cuts, as it cleans, if left alone & no possible way can you do anything once after the stone has been set !!
Please excuse my roughly-drawn diagrams, I’m not a MIchelangelo, but just a ‘setter’,:>)
I won’t go into how to finish the filing/trimming of your stone. My reason for this ‘instructional aid’ is very simple! I want to give you some options in preparing all of the techniques into getting your Diamond or Gemstone into your ring & what to look for. There are so many techniques to remember, trust me!
Diamond & 
Gem-stone setting is really an easy task, I always say…'The first 5,000 rings are the hardest, then it becomes easier!"