Value Addition in Gemstones by Nuclear Techniques
Abstract
Northern areas of Pakistan are rich in minerals and different types of precious/ semi-precious gemstones. One of these gemstones called topaz is quite abundant in Gilgit-Baltistan, Skardu and Kashmir regions. Although, topaz is a semi-precious stone but pink topaz from Mardan district in KPK province has a high worth in its natural form because it is rare in the world. In general, topaz is a colorless transparent stone, which is not very expensive. These semi-precious stones can be made precious by adding colors using different treatments like thermal heating, electron beam exposure, gamma rays or neutron irradiations. Except for electrons and neutrons, all other treatments give brown, golden or light blue colors, which are of low worth. The colors are usually not stable and fade away with the passage of time. About 30-40 times value can be added if the color is persistent dark blue. This deep blue color in topaz can be produced by neutron irradiation from a nuclear reactor. At present, for semi-precious stones, the world market is in the hands of blue topaz; typically named as Sky blue, Swiss blue and London blue. Countries like Indonesia, Thailand and US are already in this business and making significant profit. Pakistan Research Reactor (PARR-1) at the Pakistan Institute of Nuclear Science & technology (PINSTECH) has the capability to produce these desirable colors. Therefore, handsome revenue can be generated by utilizing this methodology. Apart from this, the other benefits are the development of a useful technology, collaboration between public and private sectors and application of nuclear techniques for peaceful purposes, which is one of the objectives of Pakistan Nuclear Society (PNS).
References
Pala International, “Pakistan’s gemstones: An Overview”, Live Oak Park Road, USA, 2008
URL:http://www.palagems.com/pakistanoverview.
C.S. Hurlbut and C. Klein, “Manual of Mineralogy”, John Wiley and Sons Ltd, 20th edition, ISBN 0-471-80580, 1985.
Mineralogy Database, “Topaz mineral data”, Themes Valley Minerals, Morocco, 1990 URL:http://www.webmineral.com/data/topaz.shtml
W. Ying and G.Y. Bao, “Research on radiation-induced color change of white topaz”, Radiation Physics and Chemistry, vol. 63, pp. 223-225, 2002.
L. Pauling, “The crystal structure of topaz”, Proceeding of the National Academy of Sciences, USA, vol.14, 1928.
D.N. da Silva, K.J. Guedes, M.V.B. Pinheiro, J.M. Spaeth and K. Krambrock, “The microscopic structure of the oxygen–aluminium hole center in natural and neutron irradiated blue topaz”, Physics and Chemistry of Minerals, vol.32, pp. 436-441, 2005.
K. Krambrock, L.G.M. Ribeiro, M.V.B. Pinheiro, A.S. Leal, M.A. de Barros Correia Menezes and J.M. Spaeth, “Color centers in topaz: comparison between neutron and gamma irradiation”, Phys. Chem. Minerals, vol. 34, pp. 437-444, 2007.
T. Rauch and M. Würtenberger, “Method of coloring cut gemstones”, US Patent, 7033640, 2006.
K. Nassau, “The origins of color in minerals”, American Mineralogist, vol. 63, pp. 219-229, 1978.
K. Nassau, “The Physics and Chemistry of Color”, Wiley, New York, 1983.
K. Krambrock, M.V.B. Pinheiro, K.J. Guedes, S.M. Medeiros, S. Schweizer and J.M. Spaeth, “Physics and Chemistry of Minerals”, vol. 31, pp. 168, 2004.
M. A. Wahab, “Solid State Physics”, 2nd Edition, Narosa Publishing House, India, 2005.
A.S. Leal, K. Krambrock, L.G.M. Ribeiro, M.Â.B.C. Menezes, P. Vermaercke and L. Sneyers, “Study of neutron irradiation-induced colors in Brazilian topaz”, Nuclear Instruments and Methods-A, vol. 580(1), pp. 423-426, 2007.
S.O. Olabanji, O.A. Ige, C. Mazzoli, D. Ceccato, J.A. Akintunde, M. De Poli and G. Moschini, “Accelerator-based analytical technique in the evaluation of some Nigeria’s natural minerals: Fluorite, tourmaline and topaz”, Nuclear Instruments and Methods-B, vol. 240(1-2), pp. 350-355, 2005.
K. Boonsook, W. Kaewwiset, P. Limsuwan and K. Naemchanthara, “Gamma ray evaluation of fast neutron irradiated on topaz from Sri Lanka by HPGe gamma ray spectrometry”, J. Physics: Conference Series, Siam Physics Congress, vol. 901, 2017.
A.M. Akhanov, M.T. Aitkulov, D.S. Sairanbayev, Sh.Kh. Gizatulin, N.K. Romanova, A.A. Shaimerdenov, Y.V. Chikhray, Zh. Ualzhanov and T.K. Zholdybayev, “Irradiation capsule design for neutron coloration of topaz in a WWR-K reactor”, Applied Radiation and Isotopes, vol.190, pp. 110472, 2022.
C.S. Hurlbut, and R.C. Kammerling, “Gemology”, NY: John Wiley & Sons, Inc., 1991.
M. Wasim, W. Zafar, M. Tufail, M. Arif, M. Daud and A. Ahmad, “Elemental analysis of topaz from northern areas of Pakistan and assessment of induced radioactivity level after neutron irradiation for color induction”, J Radioanal Nucl Chem, vol. 287, pp.821–826, 2011.
C.E. Ashbaugh, “Radioactive and radiation treated gemstones”, Radioactivity & Radiochemistry, Vol. 2(1), pp. 42–57, 1991.
J. Zhang, T. Lu, M. Wang and H. Chen, “The radioactive decay pattern of blue topaz treated by neutron irradiation”, Gems & Gemology, vol. 47(4), pp. 302-307, 2011.
