A hand faceter, also known as a jamb peg, is the simplest form of faceting device: a vertical peg or post fixed into a flat board, around which a series of notches or holes are cut at predetermined angles. The lapidary rests the dop — the metal rod to which the rough stone is cemented — against the peg at a chosen notch, then manually rotates the dop while pressing the stone against a horizontal revolving lap charged with abrasive. The result is a flat, polished facet ground at the angle dictated by the notch position. By moving the dop from notch to notch and rotating it through successive positions, the cutter builds up a complete faceted stone.

Historical context

The jamb-peg principle predates the development of modern indexed faceting machines by several centuries. Early European gem-cutting workshops, particularly those of the Low Countries from the fifteenth century onward, relied on variations of this manual approach. The cutter's skill, tactile sensitivity, and accumulated experience substituted for the mechanical precision that later instruments would provide. Well into the nineteenth century, hand-faceting methods remained standard practice in many cutting centres, and the technique persisted in parts of Asia and among individual artisan cutters well into the twentieth century.

Construction and operation

In its most basic form, the device requires only a board, a peg, and a series of notches or holes drilled at angles corresponding to common crown and pavilion facet angles — typically ranging from roughly 35° to 45° for pavilion mains and somewhat shallower angles for crown facets, depending on the gem species being cut. The dop is held loosely against the peg, allowing the cutter to feel the resistance of the lap and judge when a facet is fully formed. Rotation of the dop to successive index positions is done entirely by eye and hand, without any mechanical index wheel or protractor. Some more refined jamb-peg boards incorporate a greater number of notches, allowing finer angular increments and a wider variety of cutting styles.

The lap itself — typically a cast-iron or copper disc charged with diamond abrasive, or in earlier periods with emery and natural abrasives — rotates horizontally, and the stone is pressed downward onto its surface. The cutter modulates pressure, dwell time, and the precise seating of the dop in the notch to control facet size and meet-point accuracy.

Limitations and accuracy

The principal limitation of the hand faceter is repeatability. Because angle and index position are set by feel rather than by a calibrated mechanical stop, achieving perfectly matched facets across a stone demands considerable skill and practice. Meet points — the precise junctions where three or more facets converge — are difficult to control consistently, and slight variations in how the dop seats against the peg from one facet to the next introduce cumulative error. For this reason, stones cut on a jamb peg typically show less geometric precision than those produced on a modern faceting machine equipped with a calibrated index wheel and a vernier angle adjustment.

Despite these constraints, skilled practitioners can produce work of remarkable quality. The hand faceter rewards sensitivity and patience, and some experienced cutters argue that the direct tactile feedback it provides develops a more intuitive understanding of how a stone responds to the lap than mechanical equipment alone can teach.

Contemporary use

Modern indexed faceting machines — which lock the dop at precise angular and rotational positions — have largely supplanted the jamb peg in professional and competitive cutting. Nevertheless, the hand faceter retains a place in lapidary education as a teaching tool: because it strips away mechanical assistance, it obliges the student to understand the geometry of faceting directly. Some lapidary schools and gem-cutting clubs introduce beginners to the jamb peg before progressing to indexed equipment, on the grounds that the discipline it demands builds foundational skills. A small number of traditional cutters in South and Southeast Asia continue to use jamb-peg variants for commercial production, particularly for smaller calibrated stones where speed and low equipment cost outweigh the precision advantages of indexed machines.