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Colored Diamonds - HPHT Process

Exemple of HPHT Process

HPHT Enhancement Process
  • Before
  • After
Another color enhancement process that we use on certain diamonds is HPHT. An HPHT stand for High Pressure High Temperature, which is very similar to nature treatment, is a process which is very similar to nature, putting the diamond back into the environment in which is formed.

At the beginning in 1980 HPHT used to tu yellow

Different elements trapped in the molecular structure cause color in natural diamonds. For example, blue diamonds are a result of the presence of boron in the diamond. The HPHT process recreates the high pressure and high temperature conditions that existed naturally within the mantel of the earth during the formation of the diamond to allow these different natural elements to relax and display their natural color. Highly sophisticated machines expose the diamond to heightened heat and pressure resulting in the change of color. The main limitation of this process is the requirement of using very clean diamonds (VS1 clarity and better), for any small feathers in the diamond will result in worsening or even chipping of the diamond during the exposure to high pressure.

The HPHT process is absolutely permanent and irreversible. There is no need to avoid extreme temperatures as with other color treated diamonds. Because the process is permanent, it is possible to obtain GIA or EGL certificates for HPHT-treated stones.

HPHT-treated diamonds offer excellent value, as they are of high color and clarity but are less expensive than untreated stones.

HPHT Price comparison

Non HPHT Diamond

  • Natural Diamond
  • 3.12ct Marquise Shape
  • Excellent Cut
  • D Color
  • IF Clarity
  • GIA Certificate
  • $190,000 - $210,000

HPHT Diamond

  • Natural Diamond
  • 3.12ct Marquise Shape
  • Excellent Cut
  • D Color HPHT
  • IF Clarity
  • GIA Certificate
  • $90,000 - $105,000

Important to know

Color Enhanced Diamonds must always be advertised as such. Diamonds that have been irradiated must also be so identified by jewelers as enhanced diamonds, or treated diamonds.
If you are in the market for Color Enhanced Diamonds make sure that the certification you receive with the stone is clearly identified as either natural color or enhanced color. The U.S. Federal Trade Commission (FTC) requires disclosure of gemstone treatments (enhancements) at every level of the trade.
Do not forget when buying a Color Enhanced Diamonds make sure to ask your seller to provide you with a certificate of authenticity for your diamond.

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