An annulet is a plain circular ring. It’s an ancient charge, dating from c.1255 in the arms of Plessis or Plescy [ANA2 10]. In the earliest blazons, it was sometimes called a “false (i.e., voided) roundel”, but soon became recognized as an independent charge. In the English system of cadency, the annulet is the brisure of the fifth son.
Armory with multiple annulets will normally have them separate on the shield, as with any other charge, but they may also be “interlaced” or “braced”: the illustration shows three annulets braced two and one, as in the arms of Huberk or Hawberk, c.1460 [RH]. Concentric annulets may also be termed “vires”: i.e., “Three concentric annulets” and “Three vires” are equivalent blazons, being an early depiction of the gurges.
Anne des Anneaux bears: Purpure, five annulets in saltire Or.
Carl of Carolingia bears: Argent, three annulets azure.
Margie of Glen More bears: Vert, three annulets interlaced one and two argent.