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Gemstone faceting

· 1 min read · Techniques

Illustration: Gemstone faceting

A faceted gem has flat, polished surfaces (facets), placed precisely so that light enters, reflects and exits toward the eye. It is the cut for transparent stones.

Steps of the technique: Choose the design, Glue to the mast, Cut the pavilion, Move to the crown, Cut the table, Polish
Summary of the steps

The faceting machine #

The stone is glued to a rod (mast) and rests on a rotating lap. The angle and the “index” (the rotated position) are controlled precisely to cut each facet.

Stages #

  1. The pavilion (the lower part) is cut.
  2. The crown (the upper part) and the table are cut.
  3. Each facet is polished with a fine abrasive, often diamond on a lap.

Angles matter #

Each gem has a refractive index, and the pavilion angles are calculated so that light reflects inside and does not leak out the back.

Cuts #

Brilliant, princess, emerald, cushion, pear, marquise… See types of gem cut.

Step by step #

  1. Choose the design. According to stone and rough.
  2. Glue to the mast. With wax or resin.
  3. Cut the pavilion. Facet by facet with angle and index.
  4. Move to the crown. Turn the stone and repeat.
  5. Cut the table. The flat top facet.
  6. Polish. Each facet on a polishing lap.

Tools and materials #

  • Faceting machine
  • Diamond laps of various grits
  • Polishing laps
  • Cutting diagrams

Common mistakes #

  • Wrong angles: the stone loses sparkle.
  • Facets that do not meet at a point.
  • Not cleaning between laps.
  • Overheating and fracturing the stone.

See also #

This entry was drafted with the help of AI and is pending review by the author.