Spectroscopic analysis of yellow diamonds

• Author / Creator

  Lai, Mei Yan

• This research was motivated by the common recovery of yellow diamonds from kimberlites at
  Chidliak, Ekati and Qilalugaq in recent years, giving Canada the potential to become the new major
  source of fancy yellow diamonds. This thesis focuses on the analysis of yellow diamonds recovered
  from the Chidliak CH-7 and the Ekati Misery kimberlites in northern Canada. Physical properties
  including morphology, surface features and colours are recorded and displayed statistically. Further
  analyses include the extensive use of equipment – long wave ultraviolet (LWUV) (365 nm) light
  to detect fluorescence properties, Fourier transform infrared (FTIR) spectroscopy to detect the mid-
  IR absorption, UV-VIS-NIR spectroscopy to detect the visible light absorption, scanning electron
  microscope (SEM) cathodoluminescence (CL) imaging to reveal the internal growth structures,
  and secondary ion mass spectrometry (SIMS) to detect the carbon isotope composition and localized
  nitrogen concentration. The studied yellow diamonds are dominated by Type Ib/IaA, suggesting
  that the presence of C-centres is the major factor responsible for the yellow colouration of
  diamonds from both localities. The orange, yellow and green UV-excited fluorescence detected in
  some yellow diamonds indicates that the existence of additional optical centres modifies the colours.
  The discovery of diamonds from both kimberlites composed of B′-centre containing colourless
  cores and C-centre containing yellow outer layers, alongside with nitrogen thermometry results
  and evidence of distinct growth zones through different CL responses and distinct carbon isotope
  compositions, suggest that two or more episodes of diamond formation may be a common feature
  for yellow diamonds from Canada’s Arctic. Analysis of carbon isotope compositions provides preliminary
  results on the source parageneses of the yellow diamonds, where CH-7 yellow diamonds
  show a wide range of δ13C, indicative of an eclogitic (or websteritic) origin, whereas Misery yellow
  diamonds display a confined range of δ13C, in agreement with the range of mantle carbon and hence
  are thought to be mainly peridotitic.

• Subjects / Keywords

  • diamonds

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R30863N2M

• License

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