I'm no researcher, but I found this site very informative regarding rings.
Here's a short synopsis from this site (It had gobs of information regarding rings.):
Betrothal Ring. The Romans were also the first to use finger rings to "tie" people not only to their social classes, but also to their marital partners. During the betrothal ceremony the bridegroom gave a plain iron finger ring to the family of the bride as a symbol of his commitment and financial ability to support the bride. Marriages were not made in heaven but over a negotiating table. Originally the betrothal ceremony was more elaborate and important than the marriage rite, which was a simple fulfillment of the betrothal commitment. It was only much later in Christian history that the ring was made part of the wedding ceremony.
In his book How It Began Paul Berdanier claims that the binding use of the ring for betrothal ceremonies developed from an older superstitious practice in which a man tied cords around the waist, wrists and ankles of the woman he had fallen in love with, to make sure that her spirit would be held under his control. 7 The pagan superstitions surrounding the origin of the Roman betrothal ring did not deter early Christians from adopting its use. Before looking at the Christian use of the finger ring, it may be well to mention a few pagan superstitions associated with the finger ring. This will help us place the wedding ring in its historical context.
Other topics:
The "Magic Power" of Finger Rings
Poison Finger Rings
Astrological Finger Rings
Implications of Ring’s Pagan Origin. The few examples cited above about the various superstitious and idolatrous use of finger rings are far from being exhaustive. The major encyclopedias I have consulted have lengthy articles describing the superstitious use of finger rings as charms, amulets, talismans, and as aids to the worship of various pagan gods. 13 What has been mentioned should suffice to show that the origin of the finger ring is to be found in pagan superstitions and idolatrous practices.
The pagan origin and meanings of the finger ring raise questions about the legitimacy of its adoption by Christians to represents marital commitment. In the Bible the value of symbols is determined by their origin and meaning. The Sabbath, the Passover lamb and blood, the Lord’s Supper, baptism, and footwashing are all valuable symbols, because they have been established by God to help us conceptualize and internalize spiritual realities. Their value is derived from their divine origin, meaning, and function. By contrast, the meaning of the wedding ring as a symbol of marital commitment finds its origin not in Scripture, but in pagan mythology and superstitions. To invest a pagan symbol with a sacred Christian meaning, can easily lead to a secularization of the symbol itself. As we shall see, this is exactly what has happened with the use of the wedding ring.
http://www.biblicalperspectives.com/books/christian_dress/4.html
