Color - The 4 Cs of Gemstones

The most precious gemstone, the diamond, is graded based on the 4 Cs: Cut, Color, Clarity, and Carat. With colorless diamonds, every one of these specifications equally matters. When it comes to color diamonds, and colored gemstones for that matter, color takes precedence. After all, a gemstone’s color is truly what sets it apart from other stones.


Gemstone color can be broken down into three categories: hue, tone, and saturation. The first factor, hue, refers to the specific color of the stone. It is preferable for a stone to have the purest hue possible. This means that any secondary color should either be nonexistent or minimal. The second factor, tone, describes the level at which the color is seen in the stone. A gemstone can be green, but it can be a very light shade of green or display an extremely deep green color. Lastly, the saturation of a stone is how strongly the stone’s color shows versus any possible gray or brown hues that may be present in the stone.


There are some gemstones that can be found in completely different colors, so it is important to ensure that both the gemstone and the color are correct. For example, sapphires can be found in either pink, white, yellow, or the mast familiar – blue. Ruby, aquamarine, and emerald can only be found in red, blue and green, respectively, but stones like tanzanite and tourmaline can be found in more than one color as well.




Before the color of any gemstone, can be assessed, its color must first be established. A gemstone appraiser makes sure, for example, that the blue stone that he is looking at is a tourmaline and not a sapphire, or a tanzanite and not an aquamarine.


An Aquamarine and a Sapphire next to each otherAn Aquamarine and a Sapphire next to each other



It is the most desirable for a gemstone to possess a pure color, but more often than not, a stone also has secondary colors. For example, a very valuable ruby may display a pure blood red color, or otherwise they can range from pink to the darkest purple. A pure color can be one of the primary colors, red, blue, and yellow, while secondary colors are those created as a result of primary colors mixing, such as purple, green, and orange.

Pinkish Red Marquise Ruby and Diamond Ring

A Pinkish Red Marquise shaped Ruby and trilliant cut diamond 3 stone Ring



The tone of a gemstone is graded based on how deep the color shows. This can be anywhere from colorless to black. As a result, the tone categories are defined in the following manner: very light, light, medium-light, medium, medium-dark, and dark. As can be expected, the stones that are most sought after in terms of quality, beauty, and color are stones that fall into the medium-light to medium-dark range. The presence of either black or white color in a gemstone is what essentially determines a stone’s tone. If a stone has a high percentage of black mixed in with the primary color, the stone will have a dark tone, whereas a stone that contains white color can be very light. It is not ideal for a gemstone to be too dark or too light, although that may change the price of the stone in your favor.

2 Sapphires in different tones of blue

2 Sapphires in different tones of blue




While color is very much desirable in a colored gemstone, and it is preferred for stones to have some traces of black or white, it is very much not desirable for a stone to contain gray or brown color. The less gray and brown in a stone, the higher the saturation level. A stone containing zero gray or brown has yet to be discovered, but if were to be, it would be considered a stone with a 100% saturation. Gemstones with high color saturation are referred to as stones with vivid or strong saturation.


A pure red ruby

A pure red ruby with no gray or brown coloring



As a gemstone’s most unique quality, it is crucial to understand the color in gemstones and how it is assessed. Having said that, the other Cs must be factored in as well. If size is of great importance, then the stone’s carat weight cannot be ignored. The same goes for the clarity and cut of the stone.

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