This precious gem stone is based on corundum. While the blue sapphire gemstone is the best known variety, this precious gem stone comes in a range of colors (fancy sapphires) including pink, orange, purple, yellow, blue and white. In its most pure form, the sapphire is transparentBlue sapphires are evaluated based upon the purity of their primary hue. Purple, violet and green are the normal secondary hues found in blue sapphires.Violet and purple can contribute to the overall beauty of the color, while green is considered a distinct negative. Blue sapphires with no more than 15% violet or purple are generally said to be of fine quality. Blue sapphires with any amount of green as a secondary hue are not considered to be fine quality. Gray is the normal saturation modifier or mask found in blue sapphires. Gray reduces the saturation or brightness of the hue and therefore has a distinctly negative effect.
