Are Diamonds With Black Spots Cheaper?
Understand how internal features, commonly called "black spots," affect diamond value and how to evaluate them.
Diamonds, cherished for their brilliance and beauty, are natural wonders formed deep within the Earth. As with any natural creation, they often possess unique internal characteristics, sometimes referred to as “black spots.” Understanding these natural attributes, particularly what causes black spots and how they are evaluated, offers valuable insight into a diamond’s overall characteristics.
Understanding Black Spots in Diamonds
“Black spots” in diamonds are a common term for specific types of internal features known as inclusions. These are typically tiny crystals of carbon, often graphite, or other minerals that were trapped within the diamond during its formation process. Diamonds crystallize under immense heat and pressure in the Earth’s mantle; during this process, not all carbon atoms fully crystallize, or other minerals become encased.
These inclusions are not surface blemishes but are entirely internal, sealed within the diamond’s structure. Their appearance can vary, ranging from microscopic pinpoints to more noticeable specks or even cloud-like formations. While often appearing black due to their opaque nature and contrast against the diamond’s clarity, they can also be dark-colored crystals of other minerals like olivine or garnet.
How Black Spots Affect Diamond Value
Black spots generally lead to a lower diamond value because they directly impact a diamond’s clarity grade. Clarity is one of the “4Cs” (Cut, Color, Clarity, Carat Weight) used to assess diamond quality. Inclusions, especially those visible to the naked eye, reduce a diamond’s clarity rating, which is graded on a scale ranging from Flawless (FL) to Included (I). Flawless diamonds contain no inclusions or blemishes visible under 10x magnification.
The size, number, and location of black spots significantly influence their visibility and impact on value. Larger or more numerous spots, particularly those located centrally or directly under the diamond’s table, are more noticeable and can disrupt the diamond’s light performance, affecting its brilliance, fire, and scintillation. This diminished light performance and visual appeal result in a significant price reduction. Diamonds with black spots noticeable to the unaided eye fall into the Slightly Included (SI) or Included (I) clarity grades.
Assessing Diamonds with Black Spots
When considering a diamond that has black spots, understanding its grading report is a first step. Reputable gemological laboratories, such as the Gemological Institute of America (GIA) and the American Gem Society (AGS), provide detailed reports that include a clarity grade and often a plotting diagram showing the type, size, and location of inclusions. These reports are based on examination under 10x magnification.
A key concept in assessment is “eye-cleanliness,” which refers to whether inclusions are visible to the naked eye without magnification. Physically examining the diamond under various lighting conditions is advisable, as the visibility of black spots can change with different light sources. Additionally, the choice of setting can sometimes help conceal inclusions, particularly if they are near the diamond’s edges or girdle.