Adapted from online sources: bullion wire is an embroidery material made entirely from metal and a small portion of gold. Despite also being referred to as “goldwork,” actual gold bullion accounts for a trace amount of its material. Traditionally, the number would have been 2 percent, but it’s more common today for bullion wire to be made from a mixture of white metals and 0.01 percent gold called “gilt.”

To utilize bullion wire, embroiderers cut the tightly spun coil into small pieces that are then stitched onto the top of fabric. This fine technique, which originated in Medieval England as a way to embellish priestly vestments, was later applied to military and ceremonial uniforms as well as blazer crests signifying membership in schools, clubs or army regiments.