Refers to a grading scale for diamonds in the normal color range used by internationally recognized laboratories (GIA & IGI for example). The scale ranges from D which is totally colorless to Z which is a pale yellow or brown color. Brown diamonds darker than K color are usually described using their letter grade, and a descriptive phrase, for example M Faint Brown. Diamonds with more depth of color than Z color fall into the fancy color diamond range.
Diamond color is graded by comparing a sample stone to a master stone set of diamonds. Each master stone is known to exhibit the very least amount of body color that a diamond in that color grade may exhibit. A trained diamond grader compares a diamond of unknown grade against the series of master stones, assessing where in the range of color the diamond resides. This process occurs in a lighting box, fitted with daylight equivalent lamps. Accurate color grading can only be performed with diamond unset, as the comparison with master stones is done with diamond placed on its table facet and pavilion side facing upwards. When color grading is done in the mounting, the grade is expressed as an estimated color grade and commonly as a range of color. Grading mounted diamonds involves holding the mounted diamonds table close to the table facet of the master stone and visually comparing the diamond color under the same color conditions as unmounted diamond grading. The resulting grade is typically less accurate, and is therefore expressed as a range of color. While a grading laboratory will possess a complete set of master stones representing every color grade, the independent grader working in a retail environment works with a smaller subset of master stones that covers only the typical grade range of color they expect to encounter while grading. A common subset of master stones would consist of five diamonds in two grade increments, such as an E, G, I, K, and M. The intermediate grades are assessed by the graders judgement.
Diamonds in the normal color range are graded loose, (for example F-G)
|GIA||Status: current||AGS||Status: current||AGS||Status: historical: pre 1995||CIBJO||Status: current||IDC||Status: current||Scan. D.N.||Status: current||Old World Terms||Status: historical|
|grade and description||grade and electronic colorimeter scale||grade and electronic colorimeter scale||grade||grade and description||grade for .50ct and over||grade for under .50ct||series 1 scale||series 2 scale|
|D||Colorless||0||0–0.49||0||0–0.75||Exceptional white +||Exceptional white +||Colorless||River||White||Finest White||Jager|
|E||0.5||0.5–0.99||Exceptional white||Exceptional white||River|
|F||1.0||1.0–1.49||Rare white +||Rare white +||Colorless when viewed through the crown||Top Wesselton||Fine White|
|G||Near Colorless||1.5||1.5–1.99||Rare white||Rare white||Top Wesselton|
|I||2.5||2.5–2.99||4||2.51–3.0||Slightly tinted white||Slightly tinted white||Slightly colored||Top Crystal||Slightly tinted white||Commercial White||Top Crystal|
|J||3.0||3.0–3.49||5||3.01–3.75||Crystal||Top silver cape||Crystal|
|K||Faint Yellow||3.5||3.5–3.99||Tinted white||Tinted white||Top cape||Tinted white||Top cape|
|M||4.5||4.5–4.99||7||4.51–5.50||Tinted color 1||Tinted color||Slightly colored to colored||Cape||Tinted color||Light cape||Cape|
|N||Very Light Yellow||5.0||5.0–5.49||Tinted color 2||Low Cape|
|O||5.5||5.5–5.99||8||5.51–7.0||Light yellow||Cape||Very light yellow|
|S||Light Yellow||7.5||7.5–7.99||Tinted color 3||Yellow|
is one of four major characteristics that are considered when determining a diamond's quality and value. They are known as theFour C's, and the remaining three are clarity, cut, and carat weight.Understanding these four diamond characteristics and how they interactcan help you select a diamond that suits your tastes and yourpocketbook.
Diamond Color Variations Diamonds are not all truly colorless, but it's the colorless diamonds, sometimes called white diamonds, which all other shades are judged against. The Gemological Institute of America (GIA) has devised a set ofguidelines to grade diamond color. The color of graded diamonds iscompared to the color of control stones, preselected gems of a specific color.
Diamond Color Grading Procedure *To be graded, diamonds must be loose stones, because once a diamond is set into metal the metal can affect its color. *Diamonds are placed table-down, pavilion-up and viewed with a 10X loupe. *A lettering system from D to Z is used to identify theamount of color present in each diamond, with D awarded only to rare,totally colorless diamonds.
Diamond Color Grades Colorless diamonds and diamonds that are yellow or yellowish brown aregrouped into the categories shown below. These grades do not apply to fancy colored diamonds--they have their own color grading standards.
Faintly tinted, usually yellow.
Lightly tinted, usually yellow. Tint can be seen with the naked eye.
Tinted, usually yellow, may progress to brownish. Tint visible to the naked eye, even when mounted.
Other Factors Affect Diamond Color
Fluorescence 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 ultra violet radiation. Since UV radiation is a component of daylightand is also present in fluorescent lit rooms, diamonds with thischaracteristic 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.
Diamond Color Treatments:
The color of a 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.
Choose Settings that Enhance Diamond Color:
A loose diamond that appears lightly 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.
Summing Up Diamond Color A diamond's color grade affects its price, but it isn't the most important diamond characteristic to consider before purchasing a diamond. If your budget prevents you from buying a D through F graded diamond it does not mean you can't own a beautiful gemstone. Diamond grades G through J can be fine gems and other grades may beperfectly suitable. An experienced jeweler can help you evaluate and select the best diamond for your needs.