The Journal of Gemmology2012 / Volume 33 / Nos. 1/4 The Gemmological Association of Great Britain The Journal of Gemmology / 2012 / Volume 33 / No. 1–4 The Gemmological Association of Great Britain 27 Greville Street, London EC1N 8TN, UK T: +44 (0)20 7404 3334 F: +44 (0)20 7404 8843 E:
[email protected] W: www.gem-a.com Registered Charity No. 1109555 Registered office: Palladium House, 1–4 Argyll Street, London W1F 7LD President: H. Levy Vice-Presidents: D. J. Callaghan, A. T. Collins, N. W. Deeks, E. A. Jobbins, M. J. O’Donoghue Honorary Life Members: A. J. Allnutt, H. Bank, T. M. J. Davidson, P. R. Dwyer-Hickey, G. M. Green, R. R. Harding, J. S. Harris, J. A. W. Hodgkinson, J. I. Koivula, C. M. Ou Yang, E. Stern, I. Thomson, V. P. Watson, C. H. Winter Chief Executive Officer: J. H. Riley Council: C. J. E. Oldershaw – Chairman, M. A. Burland, S. J. C. Collins, P. F. Greer, N. B. Israel, B. Jackson, A. H. Rankin, R. M. Slater, M. E. J. Wells, S. Whittaker, J. F. Williams Branch Chairmen: Midlands – P. Phillips, North East – M. Houghton, South East – V. Wetten, South West – R. M. Slater The Journal of Gemmology Acting Editor: Dr R. R. Harding Assistant Editor: M. J. O’Donoghue Associate Editors: Dr A. J. Allnutt (Chislehurst), Dr C. E. S. Arps (Leiden), Prof. A. T. Collins (London), J. Finlayson (Stoke-on-Trent), Dr J. W. Harris (Glasgow), E. A. Jobbins (Caterham), Dr J. M. Ogden (London), Prof. A. H. Rankin (Kingston upon Thames), Dr K.