Guilloché, pronounced “gee-oh-shay,” is a mechanical engraving technique, produced by a special lathe or “rose machine,” that dates to the 17th century and was popularized during the Victorian Era. Just about always applied to metal, but also common on paper currency, guilloché can be identified by patterns recalling those made on Spirograph toys of the 1960s.
In the world of wristwatches, guilloché is most frequently found on watch faces. In fine jewelry and costume jewelry, guilloché is used to enhance the appearance of brooches and pendants. Guilloché enamel refers to metal pieces that have been given the guilloché treatment and then covered with a translucent layer of enamel, giving the geometric patterns underneath the enamel a colorful hue.