Hanco Zwaan is curator of minerals and gems at Naturalis Biodiversity Center and head of the Netherlands Gem Laboratory, in Leiden, the Netherlands.

Dr. Zwaan has a PhD from Free University of Amsterdam on Geology. He specialized on the formation of emeralds, but published articles on a variety of other gemmological and mineralogical topics as well. He teaches the Netherlands Gem Laboratory’s education program in association with Gem-A, London (Gemmology Foundation and Gemmology Diploma, leading to the world-wide recognised qualification FGA), and is also involved in education leading to the European Gemmology diploma (FEEG).

Hanco Zwaan is currently president of the World Jewellery Confederation (CIBJO) Gemmological Commission, dealing with nomenclature issues and laboratory best practices. On behalf of this commission he is also co-chairing a committee on gem varietal names, dealing with variety definitions and trade names.