Gemstones have similar quality factors as diamonds(cut, clarity, color, and cut), but they are valued differently. For example, color is by far the most important C for colored gemstones, whereas cut is usually considered the most important C for diamonds.

Color: Gemstone’s color is based on the purity of its hue, depth of its tone, and color saturation. These three characteristics are important in determining the value and quality of the gemstone. Most gemstones have been treated in some way to enhance their color, with the most common treatment being heat treatment. 

Hue: Hue refers to a gemstone’s actual color seen by the eye. The most valuable gemstones show a pure color and very slight hues of other colors. An example of hue is when a sapphire is described as “slightly purplish-blue” or “slightly greenish-blue.” Blue would be the primary color and with the former color being the secondary. A gemstone’s value can be greatly affected by its hue.

Tone: Tone refers to a gemstone’s lightness or darkness. Tone is described as “very light,” “light,” “medium-light,” “medium,” “medium-dark,” “dark,” and “very dark.” The most valuable and desired gemstones feature tones between the medium-light to medium-dark range. 

Saturation: Saturation refers to a gemstone’s strength of color or color purity. Saturation is judged by how much or how little gray or brown is seen in a gemstone. The most valuable and desired gemstones feature “strong” or “vivid” color saturation.

Clarity: Almost every gemstone contains inclusions. Some gemstones are even more prized with their inclusions. Gemstones that contain a small amount to a moderate amount of inclusions are typically the best value. Certain gemstones are often treated to reduce the visibility of inclusions, such as emeralds. 

Cut: Colored gemstones are different from diamonds when it comes to cut. There is not a specific “ideal” cut that produces the most brilliance. Colored gemstones are cut to show the most even, beautiful color possible while maximizing the size.

Size: Each gemstone has a different physical weight, so the actual carat weight of each is not a good representation of the visual size. Refer to the diameter of each gemstone to determine how large the gemstone will be.