The jamb peg is the traditional hand-faceting device used throughout the Indian, Sri Lankan and historical Burmese coloured-stone cutting trades, and in modified form by some specialty cutters elsewhere. It consists of a vertical wooden post (the peg) with a vertical row of small holes drilled at angle-defining heights, into which the lower end of a wooden dop stick can be inserted to hold a stone at a defined facet angle while the cutter works against a horizontal lap.

The cutter dops the rough to a wooden stick, sets the lower end of the stick in the appropriate hole on the peg, presses the stone against the spinning lap with hand pressure to grind a facet, then rotates the stick by a hand-judged angle to grind the next facet at the same height. The vertical position of the hole defines the facet angle; the rotation around the stick axis defines the position around the stone. A skilled jamb-peg cutter can produce facets of remarkable consistency by feel and eye, working without the geared faceting head used in modern Western lapidary practice.

The tool is the technological foundation of the Indian commercial coloured-stone cutting trade and is responsible for the calibrated round, oval, cushion and emerald-cut goods that flow out of Jaipur in the millions of stones per year. The Western faceting machine (the Lee, Imahashi, Ultra Tec and Facetron tradition) produces more geometrically precise individual stones but at substantially lower volume and higher cost; the jamb peg's combination of low capital cost, high cutter throughput and the trained skill of multi-generational Indian cutting families is why it remains the dominant tool in the global coloured-stone cutting trade despite being notionally less precise.