Our selection of Antique Ruby Engagement Rings derive their red color from chrome, also responsible for causing a multitude of fissures and tiny irregularities inside the crystals. Corundum is the mineralogical name for ‘aluminum oxide' covering the appropriately named Ruby as it occurs in Red and Pink, and Sapphire as it occurs in blue. Taken from the Sanscrit word ‘kuruvinda', the Ruby or ‘ratnaraj' is translated as ‘King of the Gemstones'. Graded a 9 on Moh's Scale of hardness, only a few ruby crystals grow to considerable sizes and crystallize to form a perfect gemstones, making fine Rubies above 3 karats very scarce.