Treatments / Enhancements


As with clarity, carat weight and cut, colour is also an important determining factor that influences the value of a diamond. Any alteration or manipulation of these factors will obviously have effect on the price of the gemstone.

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What you need to know about colour enhanced diamonds:

  • Colour enhanced diamonds have a lower value than unenhanced stones.
  • Diamonds of virtually any colour, including colourless, can be created artificially.
  • Several enhancement methods are used, from very basic methods to extremely sophisticated colour change techniques.
  • Identification of colour treated diamonds can be quite challenging, and often requires the use of high technology equipment. This unfortunately has a cost implication.
  • Several diamond types can be identified, based on the arrangement of its molecules or building blocks. Some of these types are more receptive to colour modification than others.
  • Colour treatments must be disclosed to the buyer, but unfortunately there is a significant risk of non-compliance to this rule. This is a fraudulent practice.
  • Because of the cost implication, it is often only feasible to request sophisticated tests for colour confirmation on the more expensive and investment diamonds.
  • The monetary implication:
    Example: If a 1ct diamond with a VS2 clarity grade gets modified from a J colour to a H grade, the price increase can amount to 1700 U.S dollars, if not disclosed.

Colour enhancement techniques:


  • The application of layers of surface coatings on the diamond.
  • Application of blue paint along the girdle (rim) of the diamond. The diamond tends to appear less yellow than it really is.

Modern Technology:

  • High Pressure High Temperature Techniques (HPHT), similar to that used in the production of synthetic diamonds.
  • Heating under low-pressure conditions.
  • Radiation treatment of diamonds, using different radiation techniques.
  • Different combinations of HPHT, Radiation and Heating processes.

Avoid Risks:

  • Fancy colour diamonds are expensive, thus the significant financial benefits that can be gained, often inspires the colour enhancement of diamonds.
  • When buying fancy coloured diamonds for investment, you should strongly consider having it tested for colour enhancements.
  • Colourless, or near colourless diamonds down to a “J “ colour grade, are more often colour enhanced than those of lower colour grades.
  • Seek independent advice from someone capable of helping you decide whether a diamond needs more sophisticated testing, to rule out colour treatments.

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FW May‘17


As with colour enhancement, any improvement in the clarity of a diamond will increase its value. Clarity enhancement therefore, has also become a tool to increase the selling price of diamonds.

Example: If a one carat diamond of colour grade H and clarity grade SI2, is enhanced to a clarity grade of VS2, the price increase can be close to 1600 U.S.Dollars, if undisclosed.    

What you need to know about Clarity Enhanced Diamonds:

Imperfections, mainly consisting of mineral crystals and cracks are the main cause of so   called “flaws” in diamonds.

  • The existence of imperfections does not necessarily lower the durability and appearance of a diamond, but will influence the grading and therefore the price. ( see under “Avoid Risks” for general care of clarity enhanced diamonds.)
  • As with other enhancement procedures, clarity enhancement should be, but not always are disclosed to the buyer. Clarity enhanced diamonds are priced significantly lower than untreated diamonds.

Enhancement Methods:

  • Crack or Fracture Filling: Surface reaching cracks are filled with transparent materials like lead glass.
  • Laser drilling techniques with or without bleaching of dark inclusions
  •  A combination of the two techniques

Avoid risks and damage:

  • Be aware of the existence of clarity enhanced diamonds.
  • Laboratory grading certificates by reputable laboratories will usually reflect clarity enhancements if present. It usually does not require sophisticated equipment (as in the case of colour enhanced diamonds) to identify clarity enhancements.
  • Fracture filled diamonds should not be exposed to acids, ultrasonic vibrating cleaners and extreme heat. For safety, do not regard the clarity of an enhanced diamond as permanent, as the filling material can be damaged.

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FW June ‘17