In 1955, some of us announced the first reproducible synthesis of diamond, with details published later. These results marked the beginning of the current synthetic diamond industry. However, there were doubts within our team from the outset regarding whether the first diamond grown using our technology (which we will call diamond number 151) was truly synthetic or merely a small piece of a natural diamond seed that accidentally entered the process. We reanalyzed diamond number 151 using modern spectroscopic techniques and found that it was indeed a small piece of natural diamond of type la.
Spectral Analysis
The spectrum shown in the figure resembles the optical spectrum of nitrogen-type la natural diamond. Specifically, there is a match in the absorption bands around 1,365 cm^-1 (associated with nitrogen plates), 1,330 cm^-1 (Raman frequency, activated by defects and impurities), 1,280 cm^-1 (from nitrogen in aggregation form ‘A’), and 1,175 cm^-1 (from nitrogen in aggregation form ‘B’). We also present the spectrum of a typical nitrogendoped synthetic diamond of type Ib, which exhibits distinctive bands at 1,130 and 1,343 cm^-1 (reference 5); none of these bands appear in diamond number 151. We conclude that diamond number 151 is a small piece of natural diamond of type la.
How Natural Diamond Entered the Experiment
It is unclear how natural diamond entered the experiment of diamond number 151, although it was discovered only a week later when the piece of iron from the experiment was being polished for metallographic examination. After our discovery of this diamond and considering it synthetic, Hall used a similar synthetic system consisting of iron/sulfur iron/graphite in his “belt” apparatus, which utilized a press and carbide cylinder to achieve high pressures. This led to further successful experiments, ultimately resulting in the development of the diamond synthesis process under high pressures and temperatures from graphite reacting with the metals and alloys of group eight, which we detailed in 1959 (after the lifting of a confidentiality order by the U.S. Department of Defense).
Our mistake was therefore a fortuitous one, as it provided the impetus to try this system under higher pressures, leading quickly to the “correct” and “reproducible” results.
References
Bundy, F. P., Hall, H. T., Strong, H. M. & Wentorf, R. H. Jr Nature 176, 51–54 (1955).
Bovenkerk, H. P., Bundy, F. P., Hall, H. T., Strong, H. M. & Wentorf, R. H. Jr Nature 184, 1094–1098 (1959).
Strong, H. M. Am. J. Phys. 57, 794–802 (1989).
Clark, C. D., Mitchell, E. W. J. & Parsons, B. J. in The Properties of Diamond (ed. Field, J. E.) 28 (Academic, London, 1979).
Chrenko, R. M., Tuft, R. E. & Strong, H. M. Nature 270, 141–144 (1977).
Hall, H. T. Rev. sci. Instr. 31, 125–131 (1960).
Leave a Reply