Delta brings decades of research (see below ) and gem-lab analysis to provide the most advanced service for certifying the origin of pink and blue/violet diamonds from the Argyle mine.

Delta principal, John Chapman, a physicist formerly working in Perth for Argyle Diamonds Ltd since its early years, has been actively studying the properties of diamonds throughout his career. Besides his own published research, he initiated and was closely involved with three PhD studies into the cause of colour in Argyle pink and blue/violet diamonds.

Argyle pink and blue/violet diamonds have been found to be notably distinctive compared with those from other deposits. Their differences are observed at the atomic level, revealed by infra-red, luminescence and visible spectra. Other distinctive features include photochromic behaviour, colour heterogeneity and visible inclusions. Analyses of all these observations are used at Delta to verify an Argyle origin, while also testing for colour treatments and coatings.

Besides Argyle origin verification, Delta is able to perform other diamond analyses such as identifying lab-grown or colour-treated diamonds, or type characterising rough diamonds.

Chapman J, Browne G, Sechos B (1996) ‘The typical gemmological characteristics of Argyle diamonds’. The Australian Gemmologist, 19(8) pages 339-346.

Chapman J, ‘Chromism is pink diamonds’ (2014). The Australian Gemmologist, 25(8) pages 269 – 271.

Chapman J, ‘Argyle Diamonds’ (2017) Diamond – the ultimate gemstone, Lithographie pages 104 - 109.

Deljanin B, Simic D, Zaisev A, Chapman J, et al, ‘Characterisation of pink diamonds of different origin’. (2008) Diamond and Related Materials Vol. 17, No. 7/10, pages 1169–1178

Byrne K.S. Chapman J.G., Luiten A.N. (2014) Photochromic charge transfer processes in natural pink and brown diamonds, Journal of Physics: Condensed Matter, Vol. 26

Shigley J.E., Chapman J., Ellison R.K. (2001) Discovery and mining of the Argyle diamond deposit, Australia. Gems and Gemology Vol. 37, No. 1, pages 26–41.

Chapman J and Deljanin B: ‘An overview of synthetic diamond detection – methods and instruments’ (2018) The Australian Gemmologist Vol 26, Nos. 9 & 8, pages 209-216