Facet – Harry & Co Jewellery

Facet arrangements and historic diamond cuts

Round brilliant cut is the most famous facet arrangement used for diamonds and colored gemstones.
The modern Brilliant Cut was devised by an Italian named Peruzzi in the late 17th century.
Marcel Tolkowsky calculated the first angles for an ideal cut diamond in 1919.
Early round brilliant cuts or Old European brilliant cuts are considered poorly cut by today's standards.
Other historic diamond cuts include the Old Mine Cut and the Rose Cut.

Faceting is an exacting procedure performed on a faceting machine.
The ideal product of facet cutting is a gemstone that displays brilliance, dispersion (fire), and scintillation.
Transparent to translucent stones are typically faceted.
Opaque materials like pleonaste and black diamond can also be faceted.
Water is used for cutting, while oil or water is used for polishing.

The angles of each facet must be carefully adjusted to maximize the optical performance of a gem.
The minimum angle for a facet to reflect light back into the gem is called the critical angle.
Gemstones with higher refractive indexes make more desirable gemstones.
Poorly cut gemstones may exhibit light leakage and windowing.
Refractive indices affect the critical angle and internal reflections.

The faceting machine uses a motor-driven plate to hold a flat disk (lap) for cutting or polishing.
Diamond abrasives are used for cutting laps, while various materials are used for polishing laps.
The machine includes an angle readout, height adjustment, and an index gear for setting the rotational angle.
A dop stick holds the stone in place, and a transfer jig is used to flip the stone for cutting and polishing both sides.
The mast and quill are parts of the machine that aid in holding and adjusting the stone.

The dopped stone is ground at precise angles and indexes on cutting laps of progressively finer grit.
Accurate repetition of angles is aided by the angle readout and index gear.
Polishing involves the use of fine abrasive particles to make minute scratches invisible.
A transfer jig is used to cut and polish both sides of the gemstone.
The process involves cutting and polishing each facet multiple times.

Reference	URL
Glossary	https://harryandcojewellery.com.au/blogs/glossary/facet
Wikipedia	http://en.wikipedia.org/wiki/Facet
Wikidata	https://www.wikidata.org/wiki/Q3268495
Knowledge Graph	https://www.google.com/search?kgmid=/m/0260kb