“Kashmir” describes sapphires that have a violetish blue to pure blue hue, with moderately strong to vivid saturation and medium-dark tone. Minute inclusions can give the gem a velvety luster and desirable softness, and also intensify its color. The color is often referred to as “cornflower blue”. “Kashmir” is widely regarded as the finest-quality blue sapphire.
“Burmese” describes sapphire that have a slightly violetish blue to blue hue, with moderately strong to vivid saturation and medium to dark tone. Their blue can be more intense and saturated than “Kashmir” sapphires, but it lacks the velvety luster. They might appear somewhat inky under incandescent light. The color is often described as royal blue. These are considered very-fine-quality sapphires.
“Ceylon” and “Sri Lankan” refer to sapphires that generally have a violetish blue to blue hue, with slightly grayish to strong saturation and light to medium-light tone. The light tone means they can return more light to the viewer’s eyes. As a result, these sapphires tend to have greater brilliance than darker-toned sapphires.
“Kanchanaburi” describes sapphires that are generally blue to slightly greenish blue, with light to dark tone. Less saturated stones typically have a grayish appearance. Most of them have minute inclusions that cause a milky appearance. They’re similar in color to Sri Lankan sapphires, but not as brilliant.
“Thai” describes sapphires that are violetish blue to slightly greenish blue, with medium-dark to dark tone. Dark tone often reduce brilliance and conceals saturation and hue. The stones are often described as inky blue or blue-black.
“Australian” refers to sapphires that are violetish blue to very strongly greenish blue, with medium-dark to very dark tone. They often show strong greenish blue pleochroism. The dark tones result in a serious reduction in brilliance, so they’re often described as inky blue.
Photo, Courtesy: GIA. Resource: Amanda. #eClarity