Portraits of the 16th and 17th centuries show that aiglets or metal tips could be functional or purely decorative, though many were used to "close" seams and slashes that are not always apparent on dark garments in portraits.
Elizabeth's aiglets were variously enameled with white, red, black, blue, and purple details or set with diamonds, garnets, rubies, and those of Anne of Denmark in the early years of the 17th century were larger, shaped in triangles and pyramids.