Since its founding in 1999, Blue Nile has grown to become the largest online retailer of certified diamonds with 30-day returns on every order. Blue Nile offers thousands of certified diamonds which can be used to create diamond engagement rings, earrings, and pendants. Every loose diamond sold by Blue Nile has been analysed and graded by either the Gemological Institute of America (GIA) or the American Gem Society Laboratories (AGSL).