Abstract
The country or mine of origin is an important economic and societal issue inherent in the diamond industry. Consumers increasingly want to know the provenance of their diamonds to ensure their purchase does not support inhumane working conditions. Governments around the world reduce the flow of conflict diamonds via paper certificates through the Kimberley Process, a United Nations mandate. However, certificates can be subject to fraud and do not provide a failsafe solution to stopping the flow of illicit diamonds. A solution tied to the diamonds themselves that can withstand the cutting and manufacturing process is required. Here, we show that multivariate analysis of LIBS (laser-induced breakdown spectroscopy) diamond spectra predicts the mine of origin at greater than 95% accuracy, distinguishes between natural and synthetic stones, and distinguishes between synthetic stones manufactured in different laboratories by different methods. Two types of spectral features, elemental emission peaks and emission clusters from C-N and C-C molecules, are significant in the analysis, indicating that the provenance signal is contained in the carbon structure itself rather than in inclusions.
Highlights
Diamonds have played a significant role in human history
Cut and polished synthetic diamonds represent the interior of the synthetic mass; less than the Value of Apparent Distinction (VAD) fall into the group of all other spectra
C, Mg, Fe, Si, Ti, Ca, Na, Ba, H, Ne, O, N, and Ar were observed in laser-induced breakdown spectroscopy (LIBS) spectra of synthetic diamonds
Summary
Diamonds have played a significant role in human history. An efficient method for transporting great value, and a component in many industrial applications, diamonds have long been useful, and their uses have evolved with human society. Diamond mining in countries with unstable governments motivated the use of diamonds to fund terrorist activities. Since 2003, international diamond trade has been led by the Kimberley Process, which defines conflict diamonds as those that “can be directly linked to the fueling of armed conflict, the activities of rebel movements aimed at undermining or overthrowing legitimate governments, and the illicit traffic in, and proliferation of, armaments, especially small arms and light weapons” [1]. Diamond mining in some countries involves significant human civil rights violations, such as indentured servitude, child labor, and inhumane working conditions [2,3,4]. All rough diamonds are exported in tamper-resistant packaging with a Kimberley Process Certificate authorized by the country of origin; import and export of rough diamonds is allowed only between Kimberley Process countries [1]
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