Pink colouration in natural diamond: optical protocols for the characterisation of crystalline colour centres

Keal Byrne

    Research output: ThesisDoctoral Thesis

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    Abstract

    [Truncated abstract] Diamond defect centres are becoming increasingly important in many fields of scientific research, yet only a few are understood to any great degree. This is particularly the case for natural diamond, in which there are many colour centres whose nature is still a mystery. This thesis focuses on one such centre: that responsible for inducing pink colouration in natural diamonds from the Argyle mine, Western Australia. This "pink colour centre" has not yet been identified, and its properties are little understood. Identification and characterisation of this defect centre has high commercial value for three distinct reasons. Firstly, as natural pink diamond is amongst the rarest and most valuable of coloured diamonds, the identification of the pink colour centre may make possible synthesis of diamonds with the same properties. Secondly, the market value of a pink diamond is predicated on the strength of its colouration. However, pink diamonds are known to demonstrate a loss of colour in certain circumstances. An analysis of the pink colour centre's optical properties will be of use in understanding this colour instability. Thirdly, given the large variety of scientific uses that diamond centres have so far found, the characterisation of this defect may very well reveal technical applications for which N-V and other defects are not suitable. This thesis describes a series of novel experiments, which have provided new insight into the electronic and physical structure of the Argyle pink diamond colour centre, and its relationship with other naturally-occurring diamond defects. The first set of experiments in this thesis focuses on the photochromism of pink diamond. The characteristic pink diamond absorption bands at 550 nm and 390 nm show a photochromic response to visible and UV light, which is long-lived at room temperature. We present a series of experiments and a related theoretical model to describe this phenomenon.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2013

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