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Judging Sapphire Quality

Color

Judging Color Is Dependent On 3 Factors

Color is affected by a gemstone’s hue, saturation and tone.  Often, multiple colors can be found in the same sapphire.

Color interpretation is unique from one person to the next. Lighting may also affect the appearance of color.  We use standard full spectrum 5000-5500 Kelvin temperature bulbs in our showroom.  This lighting is similar to the lights used in most commercial office buildings but does not have a yellowish tint and allows for a more accurate color appearance.

With these considerations taken into account, we always do our best to give our sapphires the most accurate color classifications.  Our sapphires are evaluated by two or more gemologists and the resulting color description is based on their professional opinions.

Today, gemologists seek a more universal and objective means of assessing color in sapphires.

A blue sapphire with a nice hue, a good color tone, and vivid color intensity.
A blue sapphire with a nice hue, a good color tone, and vivid color intensity.

Hue is the gemstone’s basic color.  While a sapphire’s color might be described as yellow or blue, more often gems are a combination of hues.  For example, a blue sapphire can have violet or green secondary color components that affect their beauty and value.  The hue of these sapphires would be more accurately described as violetish blue or greenish blue.

Tone, which describes how light or dark a stone’s color is, will also influence a sapphire’s value.  The preferred tones for sapphires vary from hue to hue, but most fine sapphires have a medium to medium-dark tone.  For example sapphires that have a very dark tone are often described as “inky.”

Saturation describes how pure or intense a color appears, and it is a key component in determining a sapphire’s value.  The color of a sapphire may be “diluted” with what is called a “saturation modifier.”  With cool colored sapphires like blue, green, and violet , gray is the usual saturation modifier.  With warm colored sapphires, including yellow, red, and orange , the typical saturation modifier is brown. Regardless of the sapphire’s hue, higher levels of saturation are preferred, which means their color is not diluted by modifiers.  The  finest sapphires have “vivid” saturation, but sapphires with “strong” saturation are also prized.

Natural untreated sapphire silk under magnification
Natural untreated sapphire silk under magnification

Certain inclusions like the silk seen here can actually improve a sapphire’s color.

A number of other factors may also contribute to the apparent color of a sapphire.  For example, certain inclusions can actually improve the color of a sapphire.  Minute needles of rutile silk are highly reflective and they scatter light within the stone, which may improve the apparent color.  A sapphire’s color may also depend on how it is cut.  Skilled gemstone cutters fashion sapphires to maximize their brilliance, minimize color zoning, and exhibit their best pleochroic color. After color, Clarity is just as important to a stones monetary value.

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