Relics of Christian Saints fall into four categories:

First Class Relic is the body or a portion of the body of a Saint; example: bone, flesh, or hair. These are considered so precious that they are rarely entrused to individuals, but are placed in Faith Communities.

The Second Class Relic is an item or piece of an item used by the Saint while in the body; example: clothing, Bible, Breviary, Mass vestments, and so on. Again, second class Relics are considered so precious that they are rarely entrused to individuals, but are placed in Faith Communities.

The Third Class Relic is something that has been touched to the body (or to a portion of the body) of a Saint. Generally, the Third Class Relic is a piece of cloth, but it need not be, as long as the item so touched conveys holiness and is touched with the intent that it be a third class Relic. Third class Relics may be given to individuals, and may be sold.

The Fourth Class Relic, somewhat less known, is something that has been touched to a Second Class Relic of a Saint. Generally, the Fourth Class Relic is a piece of cloth, but it need not be, as long as the item so touched conveys holiness and is touched with the intent that it be a fourth class Relic. Again, fourth class Relics may be given to individuals, and may be sold.

For more information on relics see:
http://www.greeleynet.com/~maxalla/OKHSSub/ChristianRelicRescue.html
For Devotional Medals see:
http://www.newadvent.org/cathen/10111b.htm

What is a Relic Medal:

A Third Class Relic Medal looks like the picture below.
On the back of the medal is a cloth touched to a relic of the Saint.

Disaclamer: Any medal or Relic Medal attached to our chaplets may be round or oval.
Preference to shape is not an option.

Information of interest:.
Authentic Relic of Saint Anthony: When Anthony died he was wrapped in a burial cloth (white shroud), wrapped again in a oily cloth and buried. For several hundred years that is how he remained until they enlarged the monastery, built a Cathedral etc. They exhumed St. Anthony's body, placed it in a silver casket and placed it in the Cathedral. The burial cloth they cut into 10,000 pieces and each piece placed in a medal. The pieces are held in place with "red" sealing wax. The Authentic Relic is limited. This information was given to me years ago by a friend of a Franciscan Nun.