Metals for jewellery demand precise melting and careful refining so that castings are clean, durable, and beautiful. This guide explains the Top 10 Melting and Refining Methods for Jewellery Metals in simple language, moving from workshop friendly practices to advanced laboratory approaches. You will learn what each method does, the tools involved, the quality you can expect, and where the method fits in a modern studio. By understanding heat sources, protective atmospheres, and purification routes, you will control porosity, colour, and hardness. The result is safer workflows, higher purity, and predictable results that let creativity shine without surprises.
#1 Induction Melting
Induction melting uses an alternating electromagnetic field to heat the metal inside a graphite or ceramic crucible without direct flame. It delivers fast, even heating, excellent temperature control, and minimal contamination because the coil never touches the charge. Protective fluxes or inert gas can be added to limit oxidation, and stirring from the magnetic field helps homogenise alloys like white gold and sterling silver. Power can be matched to batch size, from small benchtop units to larger shop systems. For jewellers who cast frequently and want repeatable results with fewer inclusions, induction melting is a dependable core method.
#2 Torch and Crucible Melting
Torch and crucible melting remains a versatile choice for small batches, prototyping, and repair. A neutral or slightly reducing flame from oxygen fuel or air fuel heats the metal in a clay graphite or carbon crucible, with borax based flux to dissolve oxides. The operator controls heat placement, which is helpful for high karat gold and solder alloys. Careful flame chemistry, clean crucibles, and pre dried flux limit gas absorption and contamination. Good lighting, tongs, face shield, and fume handling improve safety. When skill and care are applied, torch melting provides quick turnaround with very low setup cost.
#3 Electric Resistance Furnace Melting
Electric resistance furnaces heat a crucible through refractory elements, giving steady ramps, tight soak control, and clean operation with no combustion by products. They are ideal for predictable cycles in investment casting and for preparing alloy master grains. With programmable controllers, you can preheat flasks, dry investments, and melt metal in repeatable steps that reduce thermal shock. Lidded chambers and inert gas ports restrict oxidation and zinc loss in brass and low karat gold. Because heat is uniform, the melt stays calm, which reduces dross. Resistance furnaces shine when consistency and low maintenance are top priorities.
#4 Gas Fired Crucible Furnace Melting
Gas fired crucible furnaces use propane or natural gas to heat a refractory chamber that surrounds the crucible. They are robust, flexible with fuel choices, and can be scaled for medium batches without complex electronics. A properly tuned burner supplies a slightly reducing atmosphere to protect copper bearing alloys and to limit oxide formation on sterling silver. Regular chimney maintenance, correct flame alignment, and crucible rotation help prevent hot spots and erosion. Because heat up is fast, they suit shops that cycle between alloys through the day. For many jewellers, gas furnaces balance cost, reliability, and throughput very well.
#5 Vacuum Induction Melting and Degassing
Vacuum induction melting combines electromagnetic heating with a sealed chamber that can be evacuated or filled with inert gas. Lower pressure reduces dissolved gases such as hydrogen and oxygen, which decreases porosity and improves polish in platinum, palladium, and fine gold. Alloying additions can be weighed precisely, then stirred by the magnetic field for uniform composition. Many systems include tilt pouring into preheated ceramic shells or into controlled atmosphere molds. Although equipment cost is higher, process data such as temperature curves and chamber pressure supports strict quality control. When purity and mechanical properties matter most, vacuum induction is a standout.
#6 Arc Melting for Boutique Alloys
Arc melting uses an electrical arc struck between a tungsten electrode and the metal charge under argon to reach very high temperatures quickly. It is valuable for small ingots of platinum group alloys, titanium components in special jewellery, and experimental compositions for custom colours. A water cooled copper hearth avoids contamination, and flipping the button between strikes promotes homogeneity. Because the arc is intense, eye and skin protection are essential, and shielding gas flow must be stable. Arc melting is not a high throughput method, yet it enables boutique alloys and research grade melts that other tools cannot reach.
#7 Fire Assay and Cupellation
Fire assay with cupellation is a classic refining and analysis route that separates precious metals from lead and base metals. The sample is fused with litharge and fluxes, forming a lead button that collects gold and silver. In a porous cupel at high temperature, lead oxidises to litharge and is absorbed, leaving a bead of precious metal for weighing or further parting. For jewellers, the method verifies scrap value and reveals contamination from solder or base metal. It requires a dedicated furnace, good ventilation, and careful handling of residues. Used correctly, cupellation provides trustworthy data and a modest refining step.
#8 Miller Chlorination for Gold
The Miller process refines gold by blowing dry chlorine through molten metal at controlled temperature. Chlorides of silver, copper, and other base metals form and float as a slag, while gold remains liquid and reaches high purity quickly. The method is fast and economical for medium to large lots, often as a first stage before electrolytic polishing. Strict gas handling, refractory selection, and temperature monitoring are critical for safety and consistent results. Jewellery workshops usually contract this step, yet understanding it helps plan scrap consolidation and lot tracking. Miller chlorination delivers efficient bulk upgrading with predictable impurity removal patterns.
#9 Wohlwill Electrolytic Refining
The Wohlwill process dissolves impure gold anodes in a chloride electrolyte and plates ultra pure gold onto cathodes under controlled current density. Impurities fall as anode slime that can be recovered for silver, platinum, and palladium. This technique achieves very high purities suitable for critical settings, fine wires, and luxury watch components. Parameters such as voltage, temperature, and agitation are tuned to maintain smooth deposits and high current efficiency. Although capital cost and cycle time are higher than Miller, the final product is exceptional. For premium lines that demand consistent colour and alloy accuracy, Wohlwill refining is ideal.
#10 Aqua Regia Wet Chemical Refining
Aqua regia refining dissolves gold using a mixture of nitric and hydrochloric acids, followed by selective precipitation, filtration, and washing to obtain fine metal. It is flexible for mixed jewellery scrap, dental alloys, and small batches where individual control is important. Silver forms an insoluble chloride and is recovered in a separate stream, while palladium can be precipitated with dedicated reagents. Careful control of temperature, acid ratios, and rinsing reduces residual chlorides that can embrittle alloys. Because strong acids and fumes are involved, trained personnel, fume hoods, and neutralisation plans are mandatory. When managed professionally, aqua regia gives reliable high quality feedstock.