DILL, H.G. and WEBER, B. (2013) Gemstones and geosciences in space and time. Digital maps to the „Chessboard classification scheme of mineral deposits“.- Earth Science Reviews , 127: 262-299 plus supplementary material (99 maps showing gemstone deposits by country, geology and geomorphology) related to this article to be found on-line at http://dx.doi.org/10.1016/j.earscirev.2013.07.006.
and the main paper "Chessboard classification scheme.."
Both are available for download from the Researchgate Server.