I got engaged on Sats. I was wearing an enormous and weird bird suit. An actual guy related to me through marriage/in-laws (so not really related to me but would be at family reunions if we gave a shazbot! about them) proposed to his girlfriend by putting the ring in a bucket of fried chicken. They were divorced a year and a half later. There's a great thread about ring shopping/proposal stories on The-Mainboard.com called "Married Men Get itt" or something. Highly entertaining.
Back to rings: I didn't really look anywhere other than the internet. Not sure how reputable bluenile.com is as far as actually adhering to their claim that the diamonds are free of human rights abuses. They might be, they might not. But I know I started looking on brilliantearth.com first and their Conflict-Free Diamonds guarantee seemed more convincing. It also seemed to me like they were kinda taking a jab at bluenile.com without mentioning them by name.
http://www.brilliantearth.com/conflict-free-diamonds/ As far as pricing goes, I think Brilliant Earth may be a little bit cheaper than Blue Nile, but the difference is probably pretty nominal.
Place had incredible customer service. Free overnight FedEx from San Fransisco got to New Orleans less than 16 hours later. 30-day free return/exchange/resize policy with no questions asked, and the packaging when they send it to you includes very specific crap about where and when it was mined (most are from Canada, Russia, or Botswana), how they pay their workers a living wage, etc. Also you can pay in installments if you are a :kugrad: . Great company. Will definitely use again for my inevitable second marriage.