Without a doubt, every diamond is beautiful, but it’s no secret that one cut stands above the rest as the most stunning diamond of all: the round brilliant cut. Achieving a perfectly round diamond took many years of research and development. Up until the late 1800s, the roundest cut achievable was the cushion cut, but with the invention of the bruting machine, diamonds were finally cut into circles, called European cut diamonds. It wasn’t until much later that round brilliant diamonds were invented, however. These came about thanks to a man named Marcel Tolkowsky who used a mathematical formula to cut diamonds proportionally. Since then, Tolkowsky’s formula has been perfected to create the 58 facets we know and love today. Check out the difference for yourself at Costco, where you’ll find great offers on truly remarkable diamond rings! And while you’re browsing, be sure to check out our stunning collection of diamond bands — the perfect accent to any engagement ring.