Sapphires are often found in larger sizes than rubies; ten to twenty carats are not uncommon. The best color is a cornflower blue, also called a Ceylon blue. This is a medium intense pure blue color with no secondary overtones to mask the original blue color. All of the other colors of sapphire (orange, yellow, pink, green) are judged by the intensity of color and the brightness or brilliance the gem displays. In the trade, a premium is paid if a sapphire comes from Kashmir (a disputed area between Indian and Pakistan) and has a deep cornflower blue color with a silky sheen so characteristic of that region. This type of gem commands a high price because of the rarity of finding such a fine gem. Most gems sold as Kashmir actually come from Burma, which also produces beautiful sapphires. Gems can be identified as to origin based on their internal inclusions and therefore, before buying always insist on a lab certificate that guarantees this provenance.

Sapphire takes it place beside ruby and emerald in being the focus of attempts to mimic its color by synthesis and/or imitation products. Since the beginning of the 1900's, synthetic sapphire has been produced. Also, synthetic star sapphires have been around since 1947. The most famous company to produce such synthetics was the Linde company and their product was called Linde star sapphire. Natural star sapphires are formed when there is sufficient rutile found within the gem's molecular lattice. When cut in a cabochon shape (domed), the six point star will reveal itself when viewed under a pinpoint light source. Star sapphires are judged by the sharpness of the star, the straightness of its "legs", whether the star is centered, and whether the legs go to the girdle's edge. In addition to these factors, the body color affects price also. Body color varies from gray to blue with blue being the most expensive.