Volume 22 No. 4. October 1990 ^{Journal of (jremmology Contents Gemstone prospects in Central Nigeria jf. Kanis and R .R. Harding 195 Hematite inclusions in Eonyang amethyst from Korea Won-Sa Kim 204 Gemmological visual aids J. Eadie 207 Bead buyers and parcel pickers filter set R.K. Mitchell 212 Water in beryl - a contribution to the separability of natural and synthetic emeralds by infrared spectroscopy K. Schmetzer and L. Kiefert 215 Gemmological teaching in Hong Kong and China J.B. Nelson 224 Detection of synthetic emeralds by thermal conductance RG. Read 233 Gemmological Abstracts 235 Book reviews 243 Proceedings of the Gemmological Association and Gem Testing Laboratory of Great Britain and Notices 246 Letter to the Editor 250 Copyright© 1990 The Gemmological Association and Gem Testing Laboratory of Great Britain Registered Office: Palladium House, 1-4 Argyll Street, London W1V IAD ISSN: 0022-1252 Produced by Green Belt Studios: Printed by Quadrant Offset, Hertford, England.