An engagement ring (or betrothal ring) is a formal gift presented during a marriage proposal, symbolizing a commitment to future marriage, and in Western cultures it is typically worn by women on the left hand's ring finger, often featuring a diamond. The tradition traces back to ancient Rome (2nd century BC), where brides received two rings—gold for public wear and iron for home—and the belief in a "vena amoris" (vein to the heart) popularized the left-hand placement, a myth later spread by Henry Swinburne in 1686. While diamonds appeared during the Renaissance, the modern association with diamonds was cemented by the De Beers Group's marketing campaign from 1939 to 1979. Historical legal and religious milestones include the Visigothic Code (mid-7th century) making the ring a binding pledge, Pope Nicholas I's 860 AD letter describing the Western custom, and the Fourth Council of the Lateran (1215) requiring public marriage banns. In some Christian traditions, the ring is blessed during betrothal, and after the wedding it is often worn on the outside of the wedding ring; contemporary scholarship also questions the old idea that the ring originated as a bride price, and customs vary globally, with some couples wearing matching rings.