Conversation so far:
when do you give an eternity ring to your wife
An eternity ring is usually given by a spouse to their wife on the occasion of a significant anniversary, typically after 10 or more years of marriage.
where did the concept of the eternity ring come from
The concept of the diamond eternity ring was created in the 1960s by diamond merchant De Beers to avoid stockpiling of small diamonds.

Question: what about the engagement ring
Self-contained rewrite: where did the concept of the engagement ring come from