Diamond color is one of four major characteristics that are considered when determining a diamond's quality and value. They are known as the Four Cs, and the remaining three are diamond clarity, diamond cut, and diamond carat weight. Understanding these four characteristics, and how they interact, will help you choose a diamond that suits your tastes and your pocketbook.
Diamonds are not all colorless, but it's the colorless diamonds, sometimes called white diamonds, that all other shades are judged against.
The Gemological Institute of America (GIA) has devised a set of guidelines to grade diamond color. Graded diamonds are compared to the color of control stones, which are preselected gems of a specific color.
Color Grading Procedure
- To be graded, diamonds must be loose, because once a diamond is set into metal the metal can affect the color we perceive. For instance, a slightly yellow diamond could look more yellow set into yellow gold, or less yellow set into white gold or platinum.
- Diamonds are placed table-down, pavilion-up and viewed with a 10X loupe.
- A lettering system from D to Z is used to identify the amount of color present in each diamond, with D awarded only to rare, totally colorless diamonds.
Colorless diamonds and diamonds that are yellow or yellowish brown are grouped into the categories shown below. These grades do not apply to fancy colored diamonds—they have their own color grading standards.
- D-E-F: Colorless.
- G-H-I-J: Nearly colorless.
- K-L-M: Faintly tinted, usually yellow.
- N-O-P-Q-R: Lightly tinted, usually yellow. Tint can be seen with the naked eye.
- S-T-U-V-W-X-Y-Z: Tinted, usually yellow, may progress to brownish. Tint visible to the naked eye, even when mounted.
GIA diamond reports and many other lab reports indicate whether or not a diamond exhibits fluorescence, which means the diamond's color changes when it is exposed to ultraviolet radiation. Since UV radiation is a component of daylight and is also present in fluorescent-lit rooms, diamonds with this characteristic can appear to change color quite often.
- Diamonds that produce a blue reaction usually appear whiter, or more colorless, under UV light.
- Stones that fluoresce yellow appear even more yellow under some lighting conditions.
The color of some diamonds can be dramatically changed by using HPHT (high pressure/high temperature) processing. Unlike diamond treatments used in the past, HPHT changes appear to be permanent.
Coatings are sometimes used to temporarily enhance a diamond's color.
Settings that Enhance Color
A loose diamond that appears light yellow to the naked eye will usually appear more colorless when mounted in a white setting—platinum or white gold. Mounting the same diamond in yellow-gold metal usually enhances the diamond's yellowish tone.
The Bottom Line
A diamond's color grade affects its price, but it isn't the most important diamond characteristic to consider before purchasing a gem. If your budget prevents you from buying a D through F graded diamond, it does not mean you cannot own a beautiful gemstone.
Diamond grades G through J can be beautiful, and other grades may be perfectly suitable. An experienced jeweler or gemologist will help you evaluate and select the best diamond for your needs.