A prong setting is the most widely used method of securing a faceted gemstone in jewellery: small metal claws extend upward from the mounting and grip the stone at the girdle or just over the crown, holding it against a seat below. Also called a claw setting in British and Commonwealth usage, the design exposes most of the stone's circumference and the entire pavilion to incoming light, which is why it has been the default for solitaires and for transparent coloured stones since the late nineteenth century.

Geometry and configurations

The standard configurations are four prongs and six prongs. Four-prong heads, frequently of the Tiffany style introduced commercially in 1886, present the stone with maximum visibility and a square or compass orientation; six-prong heads distribute load more evenly and are favoured for round brilliants where the additional contact points reduce risk of stone loss. Three-prong, five-prong, and eight-prong arrangements appear in design-led work, in step-cut mountings, and in larger stones where additional restraint is warranted. The prong tips are shaped after the stone is seated — rounded (ball), pointed (claw), flat, or V-shaped at corners of fancy cuts.

Materials and fabrication

Prong wire is fabricated from precious-metal stock chosen for springiness and wear resistance. In platinum, Pt950 with ruthenium or iridium is the workshop standard; in gold, 18ct or 14ct white, yellow, or rose alloys are used, with palladium or nickel white-gold formulations chosen for stiffness. The wire diameter must be proportionate to the stone: too thin and the prongs deform under wear; too thick and they obscure the gem and disrupt the visual balance of the head. A trained setter cuts seats into each prong with a setting bur, lowers the stone, and bends each prong over the crown using pushers and a burnisher, finishing with files and polishing wheels.

In the trade

Prong settings are the default for diamond solitaires and for transparent coloured stones where light return is the priority. They are less suitable for opaque or fragile material — opal, emerald with significant fissures, or heavily included stones — where bezel settings or protective halo designs are usually preferred. Periodic prong inspection by a jeweller is the single most important maintenance step a client can take; worn or splayed prongs are the leading cause of stone loss in fine jewellery.

Further reading

• GIA Gem Encyclopedia — settings reference
• International Gem Society — jewellery settings
• AGTA — coloured stone handling and setting