For hard-soldering a gold ring without discolouring it, use solders containing gold, which is afterwards brought to the surface by a process of annealing and pickling. The solders are prepared to suit the quality of the gold to be soldered, so that they may "colour" well and thus hide the joint. The following is a list of coloured solders: - Best solder; fine gold, 12 1/2 parts; fine silver, 4 1/2 parts; copper, 3 parts. Medium; fine gold, 10 parts; fine silver, 6 parts; copper, f parts. Common: line gold, 8 1/2 parts; line silver, 6 1/2 parts; copper, 5 parts. The solder is cast in long ingots, rolled thin and flat, and cut up, or filed into dust, and thus applied to the cleaned joints, using borax as a flux. After the joint has been closed under a blowpipe flame, the whole ring is annealed on an annealing plate to a dull red heat, then cooled, pickled in acid, and polished. The film of grease left on by the polishing process is washed off in hot soda water, and the ring dried in hot sawdust.

Hard-soldered rings may be coloured with a film of electro-deposited gold.