Rings have been found in the tombs of Ur, in Mesopotamia, dating to 2500 B.C.  While Necklaces are some of the earliest forms of adornments yet to be discovered rings are a close second.  Rings the circular shape with no beginning and no end have long had symbolic functions respecting matrimony, engagement, achievement, status or authority, as well as belonging in an organization.

Each finger of the hand had a symbolic association or meaning for the placement of a ring, significant to observers.

The fourth digit or ring finger of the left hand has become the customary place to wear betrothal, engagement and wedding rings in much of the world, though in certain countries the right hand finger is used.  The use of the fourth finger of the left hand (the 'ring finger') is associated with an old belief that the left hand's ring finger is connected by a vein directly to the heart: the vena amoris, or vein of love. This idea was in vogue in the 16th and 17th century England.

The  signet is traditionally worn on the left pinky or little finger. 

A birthstone ring and/or "birthday" stone ring is customarily worn on the first finger of the right hand.

Amulet rings, meaningful for various purposes from protection (pentacle rings) to augmenting personal attributes (wisdom, confidence, social status etc.), are worn on various fingers, often depending on the intent of the ring's design or attributes of the stone inset. Although it has been thought that amulet rings worn on specific fingers for specific purposes enhanced their powers, most people simply wear them on any finger on which they fit.

Thumb rings were originally worn to protect the thumb from injuries caused by the launching of arrows and are a sign of an archer.