This dark sulfide alloy is applied as a powder or paste into engraved lines on a host metal, usually silver or gold. The piece is then fired to melt the mixture, fusing it to the base metal. Once cooled, the surface is polished flat to reveal high-contrast black designs against the bright precious metal.
Heard on the job
We need a deeper engraving on this silver plate before applying the niello, or it will polish right out.
Insider tip
Heating the piece too quickly can cause the sulfur to burn off before the alloy melts properly, leaving a pitted finish.