Blog / Diamond Color Undertones

Many consumers today are unaware of the impact that a “color undertone” has on the appearance and ultimately the value of a loose diamond. The common misconception is that with progressively lower colors, diamonds move in a straight line from white through an increasing pure yellow. In reality, there are many color undertones other than yellow which can lead to drastically different appearing diamonds even within the same color grade.

Color Undertones Defined

Color undertones can be explained in layman's terms by thinking of them as being the hue and the combination of saturation and tone from the color spectrum. If the grade D represents the absence of any color in a diamond and Z is the most colored, the saturation of color increases progressively as you go down the color scale. Within these progressively higher color saturations in lower colors, you can have different hues of color. The most common and expected undertone hue in diamonds is yellow which is never noted in a lab report. Other hues or undertones besides yellow can also be found, the second most common of which is brown. Although more rare, greenish and grayish undertones also exist (Ref. 1-1). A gray undertone can be more clearly thought of as a tonal characteristic rather than saturation which slightly darkens the appearance of a diamond. A greenish undertone usually denotes diamonds sourced from the African country of Zimbabwe which are known for having this characteristic. In the "trade", the terminology “No BGM” (No Brown, Green or Milky) has become a commonly used term by traders to confirm that a diamond is not Brownish, Greenish or has a Milky luster. The first two terms of Brownish and Greenish are used to denote the color undertone while the term "milky" is used to define diamonds that have a slightly dull appearance without the superb luster and translucency that diamonds are known for. Milky diamonds are typically found with stones that have high levels of fluorescence. Traditionally, diamonds having an undertone other than yellow are considered undesirable by jewelers and are typically traded at a discount.

Two GIA Certified I colored diamonds, one with a yellow undertone, the other with a gray undertone
Ref. 1-1- Two GIA Certified Identical "I" Color Diamonds. Left; typical yellow undertone, Right; with a gray undertone.

Gemological Nomenclature

Lab reports from the Gemological Institute of America (GIA) Ref 1-2 and the American Gem Society (AGS) do not rate Brown or Gray undertones of a diamond that are J color and above. The color undertone of these diamonds therefore can only be judged by visual inspection.

Diagram outlining the Color Grade and Color Undertone Boundries including Fancy Colors by GIA
Ref. 1-2 Diamond Color Grade and Color Undertone Terminology Boundaries. Courtesy GIA.
  • Diamonds in the D-Z color ranges with a yellow undertone will only have their letter color grade noted on the lab report.
  • Diamonds in the D-J color ranges with brown or gray color undertones will only have their letter color grade noted on the lab report.
  • Diamonds in the K-M color ranges with brown or gray color undertones will receive a letter color grade with the addition of a "Faint *" color undertone rating. The syntax on the lab report will be the diamond’s letter color grade + “Faint *** ” Brown or Gray depending on the undertone such as "K, Faint Brown".
  • Diamonds in the N-R color ranges with brown or gray color undertones will receive a letter color grade with the addition of a "Very Light *" color undertone rating. The syntax on the lab report will be the diamond’s letter color grade + “Very Light *** ” Brown or Gray depending on the undertone such as "Q, Very Light Brown".
  • Diamonds in the S-Z color ranges with brown or gray color undertones will receive a letter color grade with the addition of a "Light *" color undertone rating. The syntax on the lab report will be the diamond’s letter color grade + “Light *** ” Brown or Gray depending on the undertone such as "U, Light Brown".
  • A diamond having a color undertone other than yellow, brown or gray and having a color grade of G and below will be graded based on the fancy color scale starting with faint such as “Faint Green”.
  • Diamonds below the Z color grade will use the colored diamond color grades and will note any color undertones if present such as Fancy Brownish Yellow which would denote a Fancy Yellow diamond that has a brownish color modifier.

Pros and Cons of Color Undertones

It is important to note that at times, a diamond having a slight brownish tint in the I,J,K color ranges can appear to face up whiter in natural daylight as opposed to a stone having a pure yellow undertone. These types of stones should be considered on a case by case basis. In many instances, diamonds having undertones other than yellow are slightly discounted due to their traditional undesirability at the wholesale level. A consumer may prefer a stone with a slight brownish tint therefore and reap a financial benefit in doing so for this reason. We recommend setting stones with a brownish undertone in rose gold which can impart an attractive peachy tone.

If a conscious decision is made to purchase a diamond with a gray, brown or greenish undertone as a matter of preference, it’s worthwhile to consider post purchase factors. Due to the stigma that these diamonds have with diamond traders and jewelers, the future resale value of these diamonds will be handicapped because of their undesirability in the trade. A professional jeweler that is offered a diamond with a color undertone will either severely under value the diamond or might refuse the transaction. This issue might arise in the future for those wanting to upgrade their diamond.

Consumers not educated in the nuances of color undertones sometimes unknowingly purchase a diamond having a tint. This is because tinted diamonds are difficult to distinguish without having an un-tinted diamond to compare it to. Experienced gemologists can recognize a brown, green or gray undertone in a diamond very quickly though. The sale of tinted diamonds is a common occurrence with diamond retailers acting as drop shippers selling diamonds based strictly on a lab report without additional imagery or videos. Diamond suppliers specifically list their undesirable, tinted diamonds with retailers that sell based on lab reports and not imagery since they are able to sneak in these stones to an unsuspecting or uneducated purchaser. It is important for the consumer therefore, at the minimum, to make their buying decision based on high resolution imagery of their diamond and not strictly based on a lab report which might not note a color undertone. Comparing numerous diamonds of the same color from the same vendor can help in the recognition of a tinted diamond.

In stark contrast to this sophisticated “drop shipper” business model, Victor Canera invests in and physically owns all diamonds available for sale in our online catalog. Our signature diamonds are manufactured to our specific proportions and tolerances. VC Diamonds are additionally strictly vetted for tint or translucency issues. This vetting of Victor Canera Signature Diamonds occurs with the physical rough diamond stage where any tinted stone is rejected prior to production. Tint and translucency issues are furthermore checked upon the completion of the polished diamond. You can rest assured that a VC Diamond will not have any “tint” issues or milkiness that might effect its translucency or performance.