Almost all diamonds grow in nature with markings inside and outside. The inside markings are called flaws/imperfections and the surface markings are called surface blemishes. Some of the typical ones are called:

  • Feathers
  • Cleavages
  • Crystals
  • Clouds
  • Bruises
  • Graining
  • Naturals
  • Twinning
  • Knots

Gemologists study five features of these markings. They are:

  • Number of flaws
  • Size of flaws
  • Types of flaws
  • Position of flaws
  • How flaws affect the passage of light through the diamond

The most universally accepted clarity grading systems are those developed by the Gemological Institute of America and the American Gem Society. The meaning given to the grades within these systems represents the industry and the legal standard. Knowing the clarity grade of your diamond is interesting and important to your insurance company, but it doesn’t give you much information about your stone. In fact, it may be successfully argued that before grading systems were available to jewelers and the public, customers learned more about their diamonds because jewelers needed to spend more time pointing out and comparing actual features of stones. In 2016, most of these features have been reduced to writing on laboratory reports, which jewelers use to position a diamond on various color and clarity scales. Here are the questions to ask your jeweler to get to know your diamond inside and out.

  • Do any of the markings affect durability?
  • If these flaws cannot be seen with the naked eye, do some of them become visible when the diamond is not clean?
  • Are any of the flaws on the edge of the diamond?
  • Do any of the flaws open onto any surface of the diamond?
  • Are any of the flaws crystals of other minerals that are typically found in diamonds?
  • Are the flaws centrally located or dispersed to the perimeter of the stone?

Asking these questions will help you understand the value of your purchase and how that value is affected by the diamond’s internal and external markings.

IMPORTANT NOTE: A clarity grade, like VS-1 or SI-1 refers to a group with thousands of diamonds with different kinds, locations and types of flaws, but all generally following the standard set for that particular group. Unfortunately most jewelers and most members of the public do not know that within every clarity grade group, there is a spread of prices, based on the analysis of the characteristics themselves. In other words, all SI-1 clarity diamonds are not the same price, even setting aside all other features of the stones. Those with flaws in the center are less expensive than those with flaws near the perimeter. Those with flaws that affect durability are less expensive, regardless of their location. Those with surface blemishes which actually open into small surface cavities are less expensive. And all of these might be accurately and ethically placed in the same clarity grade group. This is why, despite the availability of advanced laboratory reports, always discuss the characteristics of your diamond with your jeweler, to make certain you understand what you are buying and how the flaws affect its cost.

Learn more about diamond gemology:



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