From sparkling multi-million-dollar diamonds to custom designs, here are the most expensive diamond rings in the world that redefines luxury.

"Even though these are really subtle and quite small ... lab-grown diamonds: Plum Diamonds Plum Diamonds is a fantastic place to get affordable, lab-grown diamond engagement rings.

After careful consideration, we rounded up the best places to buy engagement rings: Our top pick overall is Blue Nile, which pairs an impressive diamond selection with first-rate customer service.