How Much to Spend on Your Engagement Ring
My grandfather sold a lot of engagement rings over his 50+ years at Tiffany's flagship store on Fifth Avenue in New York City. I'm sure he would have agreed "A diamond is forever," a De Beers slogan introduced during the Great Depression, a tough time to sell jewelry.
Diamond engagement rings were uncommon then, but so were divorces.
If "a marriage is forever" sounds more like what you are hoping for, you might consider spending $500 to $2,000 on the ring. Those who spend more divorce more.
From Best Bet for a Long Marriage: A Cheap Wedding with Lots of People Watching on AllGov.com, based on research by Economists Andrew M. Francis and Hugo M. Mialon, Emory University in 'A Diamond is Forever' and Other Fairy Tales: The Relationship between Wedding Expenses and Marriage Duration. The authors also conclude that more guests, lower expenses, and taking a honeymoon are also hallmarks of lower divorce risk.
Sorry, Grandpa. Maybe the diamond is better as a 25th anniversary gift.