Post subject: Confused about diamond types relative to diamond color.
Posted: Wed Jul 08, 2015 11:38 pm
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Joined: Wed Jul 08, 2015 3:31 pm Posts: 6
If the yellow color causing element in diamond is nitrogen, why are there type 1 (has nitrogen) diamonds that are graded F color and type 2a (no nitrogen) diamonds that are graded G color?
Post subject: Re: Confused about diamond types relative to diamond color.
Posted: Thu Jul 09, 2015 4:40 am
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Joined: Wed Oct 22, 2008 5:00 am Posts: 344 Location: Finland
Type I diamond (containing nitrogen) can be F color in case most of the nitrogen has grouped so that they do not cause changes in visible light absorption = color.
On the other hand, type IIa stone may have yellowish tint because of extremely small amount of single nitrogen atoms. The amount of nitrogen in this case is so small that the stone is still classified as "not nitrogen containing" = IIa. Single nitrogen in diamond just happens to be a very very strong in causing the coloration.
Also, type IIa may have a brownish tint due to plastic deformation (no foreing elements involved, just faults in crystal structure). In case of high colors it may easily get graded according to cape series (yellow) and the distinction between brown and yellow hue is not an easy call.
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