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Cutting seat on bezel setting

I have an 8.3mm round faceted gemstone that I’d like to bezel set. I ordered a custom bezel setting but the seat is too shallow, how do I go about cutting a deeper seat? I can’t find the right size setting bur, can I use an 8mm setting bur or something else?

Any tips would be greatly appreciated.



i would use a setting bur that has sides the approximate height that you want the depth of the seat to be…and then use the top of the bur as your guide…while you work your way around…the angle of the bur is the same whether big or small…

are you starting with a thick walled tube?…or cutting out of thick sheet?…


I suggest scribing a line with dividers on the inside of the bezel at depth you wish the seat to be.
Then using a small straight wall setting bur you can see past, cut your new seat at this line.
It helps if you have access to a microscope, but any good magnification will help.

It’s a custom order cast bezel setting, walls are not that thick so I’m worried about making it too thin while cutting down the seat. When ordering i wanted the seat deeper, but the cad/cam guy advised against it.


how thick are the walls…?
what is the total bezel height?
what is the total stone height?


Go very slowly. As someone said in school about diamond setting in general, “Cut a little, look a lot!”!
Use your straight walled setting burr, and watch as the flat side of your burr approaches the wall above the shallower seat.
Keep trying to fit your stone, and cut no more away than you need to fit it snugly.

I used a large straight walled setting bur and cut very little at a time, like you suggested. Success, it worked! Thank you for all the tips!


It is always good to learn that directions one gave to another " driver" did not run them off a cliff!

Glad things worked out!