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Defects in coloured natural diamonds

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Defects in coloured natural diamonds

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    2. 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.

    3. Result Brown and pink diamonds ‘Canary’ and ‘chameleon’ diamonds Australian blue-gray-violet and cape-yellow diamonds containing IR active hydrogen

    4. 1. Brown and pink diamonds

    7. Fluorescence(??)

    8. 2. ‘Canary’ and ‘chameleon’

    9. 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.

    10. 3. Australian blue-gray-violet and cape-yellow EDXRF measurements indicate that the Australian blue-gray-violet diamonds contain a very small concentration of nickel.

    11. 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)

    12. 2. ‘canary’ and ‘chameleon’

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

    14. 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. It’s unclear if the high concentration of IR active hydrogen defects has a significant influence on the Fermi-level.

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