The Journal of r Volumemmoie 28 Noemmoi. emmoi2 Apriol 200 2 o Notes from the Laboratory Chocolate- brown Opal Inclutsfbns in Gemstones Natural Amethyst hi1 (iemmoiotiuMl Asstvi.it inn .nij C iem Tcstiiv* I .ahoivitoi'v oi Crrot Britain Gemmological Association and Gem Testing Laboratory of Great Britain 27 Greville Street, London ECIN 8TN Tel: 020 7404 3334 Fax: 020 7404 8843 e-mail:
[email protected] Website: www.gagtl.ac.uk President: Professor AT. Collins Vice-Presidents: N. W. Deeks, AE. Farn, RA Howie, D.G. Kent, RK. Mitchell Honorary Fellows: Chen Zhonghui, RA Howie, RT. Liddicoat [nr, K. Nassau Honorary Life Members: H. Bank, D.J. Callaghan, E.A [obbins, H. Tillander Council of Management: T.J. Davidson, RR Harding, 1. Mercer, J. Monnickendam, M.I. O'Donoghue, E. Stern, 1. Thomson, v.P. Watson Members' Council: AJ. Allnutt, S. Burgoyne, P. Dwyer-Hickey, S.A. Everitt, J. Greatwood, B. Jackson, L. Music, J.B. Nelson, P.G. Read, P.J. Wates, C.H. Winter Branch Chairmen: Midlands - G.M. Green, North West - D. M. Brady, Scottish - B. Jackson, South West - RM. Slater Examiners: AJ. Allnutt, M.Sc., PhD., FGA, L. Bartlett, B.5c., M.Phil., FGA, DGA, S. Coelho, B.5c., FGA, DGA, Prof. AT. Collins, B.Sc., Ph.D, A.G. Good, FGA, DGA, I. Greatwood, FGA, G.M. Howe, FGA, DGA, S. Hue Williams MA, FGA, DGA, B. Jackson, FGA, DGA, G.B. Jones, B.5c., Ph.D., FGA, Li Li Ping, FGA, DGA, M. Newton, B.Sc.,D.Phil., c.I.E. Oldershaw, B.Sc.