Anvil forging is a fundamental metalworking technique in which precious metal — most commonly gold, silver, or platinum — is shaped through deliberate hammer blows delivered against a solid supporting tool: an anvil, stake, or mandrel. Unlike casting, which pours molten metal into a mould, or die-striking, which uses mechanical press force, anvil forging is a direct, hand-mediated process in which the smith reads the metal's response blow by blow, adjusting force, angle, and position continuously. The technique is central to hand-fabricated jewellery and silversmithing, and its mastery is considered a foundational competency in the bench jeweller's repertoire.

Principles of the Process

Forging works by plastically deforming metal below its melting point. When a hammer strikes metal resting on a rigid surface, the metal flows outward and downward, compressing and spreading in directions determined by the geometry of both the hammer face and the supporting tool. Because the metal is not removed — as in filing or engraving — but redistributed, forging is a highly material-efficient process. The smith can move mass from areas of excess to areas of need, thinning a shank, doming a disc, or drawing out a taper with minimal waste.

The supporting tool is as important as the hammer. A flat anvil face produces flat, spreading deformation; a curved stake or horn guides the metal into a corresponding curve; a swage — a tool with a profiled groove — forces the metal to conform to a specific cross-section, producing round wire, half-round stock, or bezel strip of consistent profile. The choice of stake profile is therefore inseparable from the intended form.

Work-Hardening and Annealing

Each hammer blow introduces dislocations into the metal's crystalline lattice, progressively increasing hardness and reducing ductility — a phenomenon known as work-hardening. In jewellery applications this is sometimes desirable: a forged shank is harder and more wear-resistant than the same alloy in its annealed state, and a forged bezel wall holds a stone more securely than one that has been left soft. However, if forging continues beyond a certain point without relief, the metal becomes brittle and will crack.

The remedy is annealing: heating the metal to a temperature at which the crystalline structure reorders itself, restoring ductility. In practice, a jeweller alternates cycles of forging and annealing throughout a piece's construction, working the metal incrementally rather than attempting to achieve the final form in a single session. The number of cycles required depends on the alloy — fine silver anneals readily and forgives aggressive working; platinum work-hardens rapidly and demands more frequent annealing at higher temperatures.

Tools: Anvils, Stakes, and Swages

The bench anvil used in jewellery work is considerably smaller than a blacksmith's anvil, typically a polished steel block of a few kilograms with a flat working face and, on many patterns, a horn or bick — a tapered projection used for forming curves and rings. Jeweller's anvils are often mounted on a wooden block or leather pad to absorb vibration and protect the bench surface.

Stakes are a family of shaped steel supports held in a bench vice or stake plate. Their profiles are highly varied:

• Flat stakes provide a level surface for planishing — the final smoothing of a forged surface with a polished hammer to remove texture and refine form.
• Mushroom and doming stakes support the formation of domed and hollow forms, including locket backs, box lids, and cabochon settings.
• Bezel mandrels and ring mandrels are tapered cylinders used to forge and true circular forms; the mandrel's taper allows the ring or bezel to be driven to a precise diameter.
• Swages are grooved blocks or plates that shape wire and strip into specific cross-sections. A half-round swage, for instance, converts flat strip into the curved profile used for box bezels and gallery wire.

Hammers used in forging range from heavy raising hammers for aggressive metal movement to lightweight planishing hammers with highly polished faces for finishing. Cross-peen and ball-peen hammers are used to stretch and move metal in controlled directions; a cross-peen blow elongates metal perpendicular to the peen's axis, while a ball-peen spreads it radially.

Applications in Jewellery Fabrication

Anvil forging appears at nearly every stage of hand-fabricated jewellery construction. Among the most common applications:

• Shank forging: A ring shank is forged from a length of square or rectangular stock, tapered at the shoulders, and trued on a mandrel. Forging produces a shank that is denser and harder at its wear surfaces than cast equivalents.
• Bezel construction: Bezel strip is forged or swaged to the correct profile, then formed around a mandrel and soldered. The walls may be forged thinner at the top edge to facilitate setting.
• Raising hollow forms: Bowls, lockets, and hollow pendants are raised from flat sheet by a sequence of hammer blows over a domed stake, progressively deepening the form. This technique — raising — is a specialised branch of forging with its own tool vocabulary.
• Texture and surface treatment: Deliberate hammer texture — planishing marks, reticulation-like facets, or controlled dimpling — is applied by forging with textured hammer faces or by striking over textured stakes.

Alloy Considerations

Not all precious metal alloys respond equally to forging. Fine silver (999) and fine gold (999) are exceptionally ductile and forge readily, but their softness makes them impractical for most jewellery applications without subsequent hardening. Standard jewellery alloys introduce hardening elements — copper in sterling silver and most gold alloys, ruthenium or iridium in platinum — that improve wear resistance but also increase the rate of work-hardening and demand more careful annealing practice.

Platinum presents particular challenges: it work-hardens quickly, requires annealing temperatures above 900 °C, and must be annealed in a clean, reducing atmosphere to avoid contamination. Conversely, its high density and malleability at working temperature make it exceptionally responsive to forging, and platinum's forged forms are notably dense and precise. Many high-end setting workshops prefer forged platinum mounts precisely because the work-hardened metal grips stones more securely than cast equivalents.

Certain gold alloys — notably some 18-carat white gold formulations containing nickel — are prone to cracking under aggressive forging and require particular care. Palladium-white gold alloys are generally more forgiving.

Historical and Contemporary Context

Forging is among the oldest metalworking techniques known, predating the development of casting by millennia in some traditions. Archaeological evidence from the ancient Near East, Egypt, and pre-Columbian Americas demonstrates sophisticated forging of gold and copper long before lost-wax casting became widespread. Medieval and Renaissance goldsmiths relied heavily on forging for structural elements, with casting reserved for decorative components that would later be assembled onto forged armatures.

The technique's continued relevance in contemporary studio jewellery is well documented in Oppi Untracht's Jewelry Concepts and Technology (Doubleday, 1982), which remains a standard reference for bench practice, and in the curricula of major jewellery schools including the Gemological Institute of America's bench jeweller programmes. Despite the widespread adoption of casting and computer-aided design and manufacture, anvil forging retains a place in high-end hand fabrication because it produces structural qualities — density, hardness, precision of form — that other processes do not replicate.

Further Reading

• GIA — Jewellery Making Techniques overview