Defects in coloured natural diamonds

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Abstract

• Characterization of different types of
  gem-quality diamonds with UV-VIS-NIR, FTIR and
  EDXRF spectroscopy reveals a number of optical
  center.
• Other optically inactive defects can have an
  effect on the colour of a diamond by influencing
  the Fermi-level.

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Result

• Brown and pink diamonds
• Canary and chameleon diamonds
• Australian blue-gray-violet and cape-yellow
  diamonds containing IR active hydrogen

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1. Brown and pink diamonds
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Fluorescence(??)
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2. Canary and chameleon
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• Both types of diamonds show yellow fluorescence
  when illuminated with long wave UV(365nm) and
  show red fluorescence when illuminated with blue
  light(450nm).
• EDXRF measurements indicate that both types of
  diamonds contain a small concentration of nickel.

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3. Australian blue-gray-violetand cape-yellow

• EDXRF measurements indicate that the Australian
  blue-gray-violet diamonds contain a very small
  concentration of nickel.

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Discussion and conclusion

• Pink and brown
• A charge or energy transfer effect and
  plastic deformation are responsible for the broad
  550nm band causing the pink colour.(pink type
  IaA/B)

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2. canary and chameleon
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• These types have a very particular
• growth history and the optically active
• defects are inhomogeneously distributed
• in these diamonds.

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3. Australian blue-gray-violet and cape-yellow
diamonds containing IR active hydrogen

• The Occurrence of phosphorescence in these types
  of diamonds.
• The influence of hydrogen on the Fermi-level is
  still a point of discussion.
• Its unclear if the high concentration of IR
  active hydrogen defects has a significant
  influence on the Fermi-level.