Medaillon

A medal or medallion is, strictly speaking, a small, flat, and round (at times, ovoid) piece of metal that has been sculpted, molded, cast, struck, stamped, or some way marked with an insignia, portrait, or other artistic rendering. A medal may be awarded to a person or organization as a form of recognition for sporting, military, scientific, academic, or various other achievements. Military awards and decorations are more precise terms for certain types of state decoration. Medals may also be created for sale to commemorate particular individuals or events, or as works of artistic expression in their own right. In the past, medals commissioned for an individual, typically with their portrait, were often used as a form of diplomatic or personal gift, with no sense of being an award for the conduct of the recipient.

An artist who creates medals or medallions is called a "medallist" (UK) or "medalist" (US). There are also devotional medals which may be worn for religious reasons. Medals have long been popular collectible items either as a variety of exonumia or of militaria. Medals may also be produced in a rectangular shape, though these would more correctly be described as a plaquette, and official awards such as military decorations are often in shapes such as crosses or stars, but are still loosely called "medals", as in the star-shaped American Medal of Honor.

In the proper use of the term, medallions are larger, starting at perhaps four inches across, and are, as such, usually too large to be worn very comfortably, though in colloquial use, "medallion" is often used to refer to a medal used as the pendant of a necklace (as in the medallion man fashion style of the 1960s and 1970s), or for other types of medals. Medallions may also be called "table medals" because they are too large to be worn and can only be displayed on a wall, table top, desk, or cabinet.

...
Wikipedia