Arc welding, as applied to jewellery manufacture and repair, is a fusion-joining process in which an electrical arc struck between a non-consumable tungsten electrode and the base metal generates sufficient localised heat to fuse metal components directly, without the introduction of a separate solder alloy. The most relevant variant for the jewellery trade is Tungsten Inert Gas welding — universally abbreviated to TIG — and its refined derivative, micro-TIG, which operates at significantly lower amperages to accommodate the delicate scale and heat sensitivity characteristic of fine jewellery work. Because the process produces a metallurgically continuous joint rather than a brazed or soldered seam, arc-welded repairs and fabrications are generally stronger, more homogeneous in colour, and more resistant to subsequent thermal stress than their soldered equivalents.

The Physics of the Arc

In TIG welding, a sustained plasma arc is established between a thoriated or ceriated tungsten electrode and the workpiece. The arc temperature can exceed 6,000 °C at its core, but the critical advantage for jewellery applications is that this energy is delivered in an extremely confined zone — typically a spot diameter of one to three millimetres — and for a duration measured in milliseconds to fractions of a second. The surrounding metal mass remains comparatively cool. This spatial and temporal precision distinguishes arc welding from conventional flame soldering or torch brazing, where radiant and convective heat spreads broadly across the piece.

An inert shielding gas — almost universally argon, or an argon-helium mixture for applications requiring a hotter, more penetrating arc — is directed coaxially around the electrode through a ceramic or glass nozzle. The gas blanket displaces atmospheric oxygen and nitrogen from the weld pool, preventing oxidation, nitride formation, and the surface discolouration (firescale) that plagues torch-based techniques on gold, platinum, and silver alloys alike. The result is a clean, bright fusion zone that typically requires minimal post-weld finishing.

Equipment: Standard TIG versus Micro-TIG

Industrial TIG welding equipment, designed for structural metalwork, operates at amperages from roughly 5 A up to several hundred amperes. Jewellery-grade TIG units are purpose-engineered for the lower end of this range, with fine amperage control — often adjustable in single-ampere increments — and foot-pedal or finger-trigger modulation that allows the operator to ramp current up and down in real time. Electrode diameters of 0.5 mm to 1.6 mm are common in jewellery workshops.

Micro-TIG welders, sometimes marketed under proprietary names but sharing the same fundamental TIG principle, push this miniaturisation further. They typically operate between 0.1 A and 25 A, with pulse durations controllable down to milliseconds. The electrode tip may be ground to a fine point under magnification, and the work is often performed under a stereo microscope or loupe. This configuration is suitable for the most demanding repair scenarios: re-tipping prongs on rings set with diamonds or coloured gemstones, closing jump rings on fine chains, reattaching micro-pavé settings, and rebuilding worn edges on platinum mounts. The heat-affected zone in micro-TIG work can be restricted to less than a millimetre, making it genuinely feasible to weld within a few millimetres of a mounted stone — a task that would be inadvisable or impossible with a torch.

Filler Metal and Joint Design

Unlike MIG (Metal Inert Gas) welding, where a consumable wire electrode doubles as filler, TIG welding is autogenous by default — the arc fuses the parent metal to itself. In jewellery practice, however, a fine filler wire is frequently introduced by hand into the weld pool when additional material is needed: to build up a worn prong tip, to fill a porosity pit, or to bridge a gap between components that cannot be brought into perfect contact. The filler wire is chosen to match the base alloy as closely as possible — 18-carat yellow gold filler for 18-carat yellow gold work, platinum 950 filler for platinum mounts, and so forth — preserving colour consistency and avoiding the differential hardness or corrosion behaviour that mismatched solder alloys can introduce.

Joint fit-up is more critical in arc welding than in soldering, because capillary flow cannot compensate for gaps the way a liquid solder can. Components to be arc welded are typically burnished, pressed, or clamped into close contact before the arc is struck. For this reason, arc welding rewards careful pre-fitting and is most efficient when integrated into a disciplined bench practice.

Metals Suitable for Arc Welding in Jewellery

• Platinum and platinum alloys — arguably the ideal material for TIG welding; platinum's high melting point (approximately 1,768 °C), low thermal conductivity, and absence of firescale make it exceptionally well suited to arc fusion. Platinum workshops were among the earliest adopters of TIG technology in the jewellery trade.
• Gold alloys (yellow, white, and rose) — all standard karatages weld successfully, though white gold alloys containing nickel can be somewhat prone to porosity if shielding gas coverage is imperfect. Rose gold's copper content demands careful amperage control to avoid overheating.
• Sterling and fine silver — weldable, though silver's very high thermal conductivity means heat dissipates rapidly, requiring slightly higher amperage settings than gold of equivalent gauge.
• Palladium and palladium alloys — weld well under argon shielding; palladium's behaviour under TIG is broadly similar to platinum.
• Titanium and niobium — used in contemporary and alternative-metal jewellery; both require particularly thorough inert-gas coverage (back-purging is sometimes employed) owing to their extreme reactivity with oxygen at elevated temperatures.

Gemstone Safety and Practical Constraints

The principal advantage that drives arc welding's adoption in repair work is its compatibility with mounted gemstones. Diamonds, rubies, sapphires, and spinels — all materials with high thermal stability — can generally tolerate the brief, localised heat of a micro-TIG pulse at a distance of two to three millimetres without risk, provided the operator works quickly and does not allow cumulative heat to build up in the mount. Emeralds, opals, pearls, turquoise, and other thermally sensitive or inclusion-rich materials require greater caution; even micro-TIG work in close proximity to these stones should be approached conservatively, with wet cotton or heat-sink compound applied as a precaution.

Stones that have been fracture-filled, clarity-enhanced with resin, or coated with thin-film treatments are at elevated risk from any heat source, including arc welding. The gemmologist or bench jeweller should identify any such treatments — ideally through laboratory documentation — before undertaking welding work on a set piece. Thermal shock from rapid localised heating can propagate existing fractures in brittle materials such as tanzanite or iolite even when the stone appears to be well clear of the weld zone.

Arc Welding versus Laser Welding

In contemporary high-end workshops, arc welding and laser welding are complementary rather than competing technologies. Laser welding (using a pulsed Nd:YAG or fibre laser) delivers an even more tightly focused energy beam and is preferred for the finest micro-repair work, for welding in recessed areas difficult to access with a TIG electrode, and for applications where the visual appearance of the weld pool must be controlled with maximum precision. TIG and micro-TIG retain advantages in cost of equipment, ease of adding filler metal, and suitability for longer seam welds or larger platinum fabrications where the laser's point-by-point approach would be inefficient. Many professional repair benches maintain both systems.

Health and Safety Considerations

Arc welding generates ultraviolet and visible radiation of sufficient intensity to cause arc-eye (photokeratitis) and skin burns on unprotected tissue. Appropriate shade-rated eye protection — typically a shade 9 to 11 auto-darkening filter for jewellery amperages — is mandatory. Argon, while non-toxic, is an asphyxiant in confined spaces; adequate ventilation is required. Metal fumes generated during welding, particularly from alloys containing nickel, cobalt, or beryllium, present inhalation hazards and must be captured by local exhaust ventilation at the bench.

Further Reading

• GIA Gems & Gemology — Laser Welding in Jewellery Repair (contextual comparison with arc techniques)
• GIA — Heat-Sensitive Gemstones and Jewellery Repair