It’s hard to imagine that a mineral with a name as mundane as corundum yields gems as exquisite as the ruby and sapphire, or even that these two stones, so different in color and mystique, are actually the same mineral family.
Lucky you if your birthstone is sapphire (September) or ruby (July). These are among the richest-colored of all gemstones with a romance and history as colorful as they are. Rubies are actually rarer than sapphires, and only red corundums are called rubies. Any other color is a sapphire. When grading colored stones, the density and hue of the color are part of the evaluation, and it’s the richest, deepest colors that are the most prized. In rubies, the most prized variant of color is called pigeon’s blood. Large gem quality rubies can be more valuable than comparably sized diamonds and are certainly rarer. There is a relative abundance of smaller, (1-3 carat,) blue sapphires compared to the scarcity of even small gem quality rubies, making even these smaller stones relatively high in value.
Stones of Burmese origin generally command the highest prices. The vast majority of rubies are "native cut" in the country of origin. High value ruby rough is tightly controlled and rarely makes its way to custom cutters. Occasionally, such native stones are recut to custom proportions, albeit at a loss of weight and diameter. Custom cut and recut stones are usually more per carat.
Sapphires exist in all the shades of blue from the deep blue of evening skies to the bright and deep blue of a clear and beautiful summer sky. Sapphires also come in many other colors, not only in the transparent grayish misty blue of far horizons, but also displaying the bright fireworks of sunset colors – yellow, pink, orange and purple. So sapphires are really and truly heavenly stones, although they are being found in the hard soil of our so-called "blue planet”.