The color of a blue star sapphire is more important than its clarity. Sapphires are rarely completely clean and even very expensive stones can be slightly included. Subtle differences in color can make great variations in valuations of fine gemstones. Fine loose gemstones of good color and clarity are always rare and valuable. Highly saturated medium or medium dark blue tones are best, blue sapphires which are too dark or too light are worth considerably less. Star sapphire's fascinating asterism is just one reason for this gemstone's popularity. As with all sapphire, they are also very durable, having a hardness of 9 on the Mohs scale. Color is the single most important factor in determining the value of a sapphire. But in star sapphires it is a combination of the body color and the distinctness of the star. Display a lighter and more intense color when viewed at different angles. Some pleochroic Sapphire is blue when viewed at one angle, and purple at a different angle. Color zoning, which forms from growth layers that build up during the formation of the stone, may also be present in certain Sapphires. Our Expert gemologists verified this Blue Star Sapphire which passed many quality base tests and get stone certified through which we are completely assured of Top Quality Gemstone. Only after that, we deliver stones to you because we also, care about your loved ones. Perfect For: Jewelers, Jewelry makers, Goldsmiths, Designers, Craftsmen, Collectors or a gift for the special one. Each and every stone is unique and you will receive ones similar to the image shown. Some rare natural sapphires exhibit a star-like phenomenon known as asterism. These gems contain intersecting needle-like inclusions (often the mineral rutile, a mineral composed primarily of titanium dioxide) that cause the appearance of a six-rayed star when viewed with a single overhead light source. To cause a star, the rutile needles need to form in parallel and tightly packed groups. The reflection off of each group of crystals forms a straight line that appears to float on the surface of the stone. There are always three groups of crystals that intersect at 60-degree angles from each other. The three lines formed connect in the center to form the appearance of a 6 ray star. The presence of a star is one of the more remarkable phenomena encountered in the world of colored gemstones. This optical phenomenon is quite rare, being only found in a tiny percentage of the sapphires mined around the world. Star sapphires can occur in any color, but the most common colors are blue, black, and pink.