Color

Ruby derives its name from the Latin word "ruber," meaning red. It is the name given to the red variety of corundum, which in any other color is called sapphire. Pink corundum is not designated as a ruby, but is instead labeled pink sapphire.

• Hue refers to the ruby's basic color - red, slight orange, strong orange, slight purple, and strong purple.
• Saturation (also called color purity and intensity) is the extent to which the hue is masked by brown or gray.
• Tone refers to the amount of color in the ruby ranging from very light to very dark.

Red ruby color table combining saturation and tone. The table on the right shows the most desirable color range.

The most sought after colors tend to be vivid, pure and highly saturated devoid of hints of brown or gray. You will often see dark black or gray areas in the ruby, known as extinction. Extinction is affected by the tone, cut, lighting quality and lighting position. Fewer areas of extinction are preferred. Lighter-colored, shallower stones normally show less extinction than darker, deeper-cut stones.

Unlike diamonds that have a 23 letter color-grading system, rubies lack a convenient method to characterize their color. This is due in large part to the extreme ranges of tone, hue and color purity in rubies. Judging the ideal color in a ruby has been largely left up to the eye of the beholder.