Niello. A metallic composition of silver, lead, and sulphur. It has been in use from the earliest times and in nearly all countries. In appearance it is a black substance, somewhat resembling enamel, but it lacks the glassy surface and has a faintly metallic lustre. It is still much used in Russia, where some very pretty pieces of jewelry are decorated with it. It is somewhat more easily achieved than enamel and wears rather better; so other points being equal, such as age, design, etc., enamel is more valuable.
An interesting account of how it was applied in the Middle Ages is given by Theophilus, the great monkish craftsman, “For laying the Niello. When you have mixed and melted the niello, take a portion of it and beat it square, long and slender. Then take the handle with the pincers, and heat it in the fire until it glows, and with another forceps, long and thin, hold the niello and rub it over all the places which you wish to make black, until the engraved designs are full, and, carrying it away from the fire, carefully make it smooth with a flat file, until the silver appear so that you can easily observe the pattern and scrape it with the cutting iron, carefully cutting away the inequalities.”
