The Refractive Index (RI) of a gemstone is the most important optical property affecting its potential brilliance (sparkle). With an RI of 2.65 – 2.69, moissanite displays more brilliance than diamond (RI 2.42) or any other popular gemstone, such as ruby (RI 1.77) and sapphire (RI 1.77). I hear ya, my eyes glazed over a bit there.