Change of cathodoluminescence spectra of natural

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Change of cathodoluminescence spectra of
natural diamond with HPHT treatment
Sim Gyu Man
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Introduction

• Some brown colored diamond changes its color to
  colorless, yellowish green
• or occasionally pink with high pressure and
  high temperature (HPHT) treatment

• The increase of color quality is welcome in
  general, but artificial treatment is a
• factor to reduce a value of gemstone in a gem
  market

• It is, therefore, important for gemologists to
  identify if a diamond has been
• treated or not

Identification methods of the treated diamond
with cathodoluminescence spectra
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Experimental
23 pieces of natural diamond was examined
HPHT with at 6 GPa and 1800-2000? for 1-5h
Cathodoluminescence measurement
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Results Discussion
An example of cathodoluminescence spectra of type
II natural diamond (a) before and (b) after HPHT
treatment.
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Results Discussion

• CL image monochromatized at 430nm. (b) and (c)
  Mapping of spectra along
• an arrow shown in (a) before and after the HPHT
  treatment, respectively.

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Results Discussion
CL spectra taken at point with 2-um interval
along a line on a diamond surface after a HPHT
treatment
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Conclusion

• It is found that the Fe band commonly
  accompanies the 2BD band
• in natural type II diamond, and that the 2BD
  bands dramatically weaken
• or disappear with heat treatment approximately
  2000? at 6 Gpa.

• The measurement of the 2BD may be available for
  identification of the HPHT
• treatment of natural type II diamond.