How can coloured diamonds turn out to be white? | BNT Diamonds
Coloured diamonds in different shades of yellow

How can coloured diamonds turn out to be colourless on the inside?

20 Jul 21
  • What human interference created these misleading diamonds?
  • How can this phenomenon occur naturally?
  • How can I be sure to buy genuine fancy coloured diamonds?

The world renowned Gemmological Institute of America (GIA) published their findings through Rapaport some time ago. The Institute discovered that certain coloured gems were not what they appeared but turned out to be colourless diamonds on the inside. How is that possible? How can I be sure to buy a genuine fancy coloured diamond for my investment?

Coloured diamonds in different shades of pink

What human interference created these misleading diamonds?

The diamond in question that caused the GIA to publish the news, was a 0.33 ct. colourless diamond coated with a thin layer of synthetic coloured diamond. It received a fancy blue grading before irregularities were discovered and initiated further tests. In-depth research uncovered the presence of both nitrogen and boron, and a mixture of type Ia and type IIb diamond, very unusual combinations indeed.

The specialised DiamondView machine showed researchers that the inside of the diamond displayed natural characteristics, whereas the outside seemed synthetic.

How can this phenomenon occur naturally?

Colour on the outside combined with a colourless inside, however, does not always point to human interference. Kashif Khan, owner of diamond auction Ritchies, discovered this first hand many years ago, when he got the opportunity to buy fancy coloured green diamonds. Contrary to other coloured diamonds, the green type does not receive its colour during their forming stage, but only after being exposed to radiation at the planet’s surface.

Khan quickly discovered that the radiation had not penetrated the complete diamond, resulting in a natural colour on the outside and no colour on the inside, causing their value to plummet. Fortunately, he was able to resell them with a profit to a fascinated geologist.

How can I be sure to buy genuine fancy coloured diamonds?

Along with the announcement that the odd fancy coloured diamond was synthetically enhanced, the GIA offered some tips on how to expose the misleading coloured diamonds. Firstly, the DiamondView brought to light certain fluorescent zones with sharp edges. These edges do not exist in natural diamonds, which show the phenomenon all the way through. Secondly, a close look reveals a straight boundary line between the thin layer of synthetic diamond and the natural gem.

Where can I buy fancy coloured diamonds as an investment? Contact the diamond experts at BNT Diamonds for guidance in your investment.

Fabienne Rauw
About Fabienne Rauw
BNT Diamonds Antwerp

Fabienne, manager of the German market is able to guide every client with finding the right jewel. She takes care of most of the German orders, but also takes other task on her plate. Thanks to her six years of experience at BNT Diamonds she acquainted well with the product and the marketing around it. Her degree in PR ensures that BNT Diamonds is well presented across all media channels. For anyone looking into a new investment opportunity, Fabienne is the perfect guide in this process. No question will be left unanswered, and she will help you every step of the way.

With this article, BNT Diamonds strives to inform you thoroughly about investing in diamonds. No investment can be guaranteed to be without risk or fully according to your expectations. That is why we recommend to research the risks and aspects of investing in diamond properly to ensure that you make the right choice for your portfolio.