Noun
eternity ring (plural eternity rings)
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 a significant anniversary.
"This would be a nice eternity ring or mother's day present," another added. Source: Internet
WHEN my married lover replaced her wedding ring with an eternity ring I gave her, I thought it meant she loved me. Source: Internet