Percent breakage for stone setting?

I am trying to get a handle on the average breakage of precious
and semi precious stones during the numerous setting procedures.
Ie. Prongs, burnish, pave', channel, etc. 

Rule #1 for setting is NOT to bust stones. Mistakes do happen,
usually caused by the naked hairless ape with the tools.

Cheap and fragile stones in tough settings and I might buy a couple
of extras (at customer expense) and expect to add them to my
inventory.

Busting a 25pt diamond takes more skill and deeper pockets than I
have, although stones with pointy corners are easier.

Setting is not rocket science, although being slightly anal really
does help. Hell they even let sort of old folks who can’t see none
too well do it.

jeffD
Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand