What is "eternity ring"

An eternity ring, also known as an infinity ring, is a lady's ring, worn on the hand, comprising a band of precious metal (usually gold) set with a continuous line of identically cut gemstones (usually diamonds) to symbolize never-ending love, usually given by a husband to his wife on the occasion of a significant anniversary, typically after 40 years of marriage. Because the presence of stones all the way round the eternity ring can make it cumbersome to wear, the alternative is to have the stones across the face of the ring only. This is sometimes referred to as a "half-eternity" ring rather than a "full" eternity ring.

Eternity rings featuring paste gems, white topaz or a mix of stones appeared in the 18th century.