Everything you need to know before buying an engagement ring

Online diamond retailer Ritani knows exactly what its customers are looking for when they visit the site: an engagement ring.

"Not only is this [ring] generally [our customer's] largest purchase to date, it's typically the millennial male, and he has no idea what he's doing," Ritani's Vice President of Marketing, Mark Keeney told Business Insider during a recent visit to their Manhattan diamond factory.

We toured the diamond factory to find out everything you need to know when it comes to purchasing a diamond engagement ring. Below, see how much people are spending, the most popular cuts, settings, and how the "four C's" can affect price.