Sapphire is one of the Big 3 of jewelry gemstones—the other two are ruby and emerald. Sapphire is a durable stone that’s the best known blue gem, as well as being available in most colors.
WHAT TO LOOK FOR
The most highly valued blue sapphires are velvety blue to violetish blue, in medium to medium dark tones. Preferred sapphires also have strong to vivid color saturation. The saturation should be as strong as possible without darkening the color and compromising brightness.
Blue sapphires often have some inclusions. Blue sapphires with extremely high clarity are rare, and very valuable. Price can drop if the inclusions threaten the stone’s durability. Kashmir sapphires contain tiny inclusions that impart a desirable velvety appearance.
To achieve the best overall color, maintain the best proportions, and retain the most weight possible, cutters focus on factors like color zoning, pleochroism, and the lightness or darkness of a stone.
Blue sapphires can range in size anywhere from a few points to hundreds of carats, and large blue sapphires are more readily available than large rubies. However, most commercial-quality blue sapphires weigh less than 5.00 carats.