The birthstone of July, rubies–which symbolize love, passion, and prosperity–are thought to bring the wearers positive energy, love, and success. The ruby is the red variety of the mineral, corundum, which is colored by the element chromium. While the latter gives rubies their red color, it also causes fluorescence, which makes them glow with a fire from within. Measuring a 9, on the Mohs scale, these tough and durable gemstones are only surpassed, on this scale, by diamonds. They are the perfect choice for many types of jewelry. Rubies have also been associated with the greater life force and the vitality of blood.