gem-peg

from The Century Dictionary.

• noun In gem-cutting, an upright double-elbowed rod of iron fixed on a lapidaries' bench near the polishing-wheel, bearing on its upper part an inverted cone of wood pierced with numerous small holes or nicks, in one of which, according to the angle desired, the lapidary rests one end of the gem-stick, thus steadying it and giving it the proper inclination while the stone glued to the other end of the gem-stick is being polished on the lap- or polishing-wheel. Also, corruptly, gim-peg, germ-peg.