Goldwork is the art of embroidery using metal threads, or threads with metal leaf wound round a normal textile thread. It is particularly prized for the way light plays on it. The term "goldwork" is used even when the threads are imitation gold, silver, or copper. The metal wires used to make the threads have never been entirely gold; they have usually been gold-coated silver (silver-gilt) or cheaper metals, and even then the "gold" often contains a very low percent of real gold. Most metal threads are available in silver and sometimes copper as well as gold; some are available in colors as well. A new coating technology however enables the direct coating of 24K gold on a filament yarn without any other metal or adhesive layer underneath.