The ruby gemstone is the epitome of fiery luxury in the jewelry world. On the Mohs scale, rubies rate a hardness of 9, leveling up with diamonds and moissanite. A familiar structural relative to the sapphire, rubies are from the prized corundum category.
Rubies generally range in pinks and intense reds. Interestingly, the ruby is so close to the makeup of the sapphire, that pink rubies are considered pink sapphires in some regards. The line often gets blurred during the classification.