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Hanco Zwaan

Hanco Zwaan

Working on understanding the factors that shape “System Earth” and what it takes to form minerals, the small building blocks, lead to a particular fascination for specific geological processes that produced beautiful, durable and rare minerals, called gemstones. Expertise on these hidden treasures of Natural History is used in our gemmological laboratory, when distinguishing those unique items from the many look-a-likes, synthetics or enhanced stones produced. 

Keywords

Geology, gem provenance, gem origin, advanced gemmology, applied research, pearl testing, mineralisation, bio-mineralisation, education

Dr. Hanco Zwaan FGA

Researcher and Head NEL

hanco.zwaan@naturalis.nl
+31 (0)71 751 9665

Linkedin

 

Research
interest

The focus of all studies is on the formation and identification of gemstones and pearls. Key is the understanding of mineralization and biomineralization.

My main research interest is to understand the specific processes that lead to the formation of gems, and how these processes link to specific events in the regional geologic history. This information can be used to better constrain ‘origin-specific’ properties that need to be determined when the (geographical) origin of a faceted gem has to be assigned. Further questions in this respect are whether this is feasible in all cases, and what is exactly needed to substantiate claims on origin of not only gems, but also pearls. These questions are relevant, in relation to fair-trade, sustainability issues and nature conservation. 

rutile needles in sapphire
two phase inclusions in flux-grown emerald

Current
topics

Key
publications

  • Zwaan J.C., Mertz-Kraus R., Renfro N.D., McClure S.F., Laurs B.M. 2018. Rhodochrosite Gems: Properties and Provenance. Journal of Gemmology 36: 332-345. 
  • Zwaan J.C., Buter E., Mertz-Kraus R., Kane R.E. 2015. Alluvial Sapphires from Montana: Inclusions, Geochemistry and Indications of a Metasomatic Origin . Gems & Gemology 51: 370-391. Go to website (DOI) 

  • Zwaan J.C., Marel D.M. van der, Dommisse H.A. 2014. The ‘Sleeping Lion’ Baroque Pearl: An Update. Journal of Gemmology 34: 248-253. Go to website (DOI)

  • Zwaan J.C., Jacob D.E., Haeger T., Cavalcanti Neto M.T.O., Kanis J. 2012. Emeralds from the Fazenda Bonfim Region, Rio Grande do Norte, Brazil. Gems & Gemology 48: 2-17.
    Go to website (DOI)

  • Zwaan J.C., Dommisse H.A. 2009. A description and history of one of the largest nacreous pearls in the world. Journal of Gemmology 31: 196-202.

  • Laurs B.M., Zwaan J.C., Breeding C.M., Simmons W.B., Beaton D., Rijsdijk K.F., Befi R., Falster A.U. 2008. Copper-bearing (Paraiba-type) tourmaline from Mozambique. Gems & Gemology 44: 4-30.

  • Zwaan J.C. 2006. Gemmology, geology and origin of the Sandawana emerald deposits, Zimbabwe. Scripta Geologica 131: 1-211.

  • Zwaan J.C., Seifert A.V., Vrana S., Laurs B.M., Anckar B., Simmons W.B.S., Falster A.U., Lustenhouwer W.J., Muhlmeister S., Koivula J.I., Garcia-Guillerminet H. 2005. Emeralds from the Kafubu area, Zambia. Gems & Gemology 41: 116-148.

  • Zwaan J.C., Cheilletz A., Taylor B.E. 2004. Tracing the emerald origin by oxygen isotope data: the case of Sandawana, Zimbabwe. Comptes Rendus Geoscience 336: 41-48.
    Go to website (DOI)

  • Seifert A.V., Zacek V., Vrana S., Pecina V., Zacharias J., Zwaan J.C. 2004. Emerald mineralization in the Kafubu area, Zambia. Bulletin of Geosciences79: 1-40.

  • Calligaro T., Dran J.C., Poirot J.P., Querre G., Salomon J., Zwaan J.C. 2000. PIXE/PIGE characterisation of emeralds using an external micro-beam. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 161: 769-774.
    Go to website (DOI)

Teaching
activities

  • Foundation and Diploma in Gemmology (FGA - BSc. eq.)

The Netherlands Gemmological Laboratory (NEL) is an Accredited Teaching Centre of Gem-A, London, and provides an internationally recognised education program in gemmology, leading to an accredited, equivalent to BSc., Degree in Gemmology. Students passing the exams receive the title FGA (Fellow of the Gemmological Association of Great Britain).   

  • European degree in gemmology (EG - HBO eq.)

The NEL is also involved in vocational teaching (cooperation with the Vakschool, Schoonhoven) leading to a HBO equivalent European degree in gemmology (FEEG, Federation of European Education in Gemmology). Students passing the exams receive the titel EG (European Gemmologist).

  • Short courses in gemmology

Short practical courses designed for gem and jewellery professionals. For further information go to  Netherlands Gemmological Laboratory (information in Dutch).

In the
media

Volkskrant 2018 - 8 februari 2018: 'Bling bling uit het lab', interview over de opkomst van de synthetische diamant.

metallic flux in synthetic diamond

Publications

2023

Journals SCI, peer-reviewed

2022

Chapters in book

Zwaan J.C. 2022. Le gisement d’émeraude de Sandawana au Zimbabwe.. In: G. Giuliani (ed.): 445 p. 81-89. Les editions du Piat. ISBN 978-2-917198-51-3.

Journals SCI, peer-reviewed

Zwaan J.C. 2022. Demantoid Garnet from Antetezambato, Northern Madagascar—Internal Characteristics and Their Use in Deciphering Geographic Origin.. Journal of Gemmology -London- 38 (2) : 64–79. DOI https://doi.org/10.15506/JoG.2022.38.1.64
2021

Journals SCI, peer-reviewed

2020

Journals SCI, peer-reviewed

Naipal R., Zwaan J.C., Kroonenberg S.B., Kriegsman L.M., Mason P.R.D. 2020. Diamonds from the Nassau Mountains, Suriname. Journal of Gemmology -London- 37 (2) : 12 p. 180-191. DOI https://doi.org/10.15506/JoG.2020.37.2.180
2019

Journals SCI, peer-reviewed

Zwaan J.C. 2019. Apatite from Durango, Mexico. Journal of Gemmology -London- 36 (8) : 683-684.
2018

Journals SCI, peer-reviewed

Zwaan J.C., Hawthorne F.C., Day M., Laurs B.M. 2018. Cat’s-eye Tremolite from Badakhshan, Afghanistan. Journal of Gemmology 36 (1) : 14-15. Journal of Gemmology, 36,1,14-15..
Zwaan J.C., Mertz-Kraus R., Renfro N.D., McClure S.F., Laurs B.M. 2018. Rhodochrosite Gems: Properties and Provenance. Journal of Gemmology 36 (4) : 332-345.
Zwaan J.C., Laurs B.M. 2018. Yellow scapolite from Tanzania showing peculiar daylight fluorescence. Journal of Gemmology 36 (3) : 198-200.
Zwaan J.C., Falster A.U., Simmons W.B., Laurs B.M. 2018. Axinite-(Mg) from Parachinar, Pakistan. Journal of Gemmology 36 (4) : 281-283.
2017

Chapters in book

Zwaan J.C., Swaving C., In: Eds. van den Bercken B.J.L., Baan V.C.P. 2017. The Original RMO Engraved Gem Collection: Gem Identification and Applied Research Techniques. Palma: Papers on Archaeology of the Leiden Museum of Antiquities. Palma 14 - Papers on Archaeology of the Leiden Museum of Antiquities: 65-74. Sidestone press, Leiden. ISBN 978-90-8890-505-6.
https://www.sidestone.com/books/engraved-gems

Journals SCI, peer-reviewed

Zwaan J.C. 2017. Enstatite from Emali, Kenya. Journal of Gemmology 35 (7) : 575-576.
Zwaan J.C., Deljanin B. 2017. A Research Facility in The Netherlands for the HPHT Growth of Synthetic Diamonds and HPHT Treatment. Journal of Gemmology 35 (6) : 491-494.
Schilthuizen M., Sipman I., Zwaan H. 2017. Sexual dimorphism in shell coloration of Plectostoma (Caenogastropoda: Diplommatinidae) is caused by polyenes. Journal of Molluscan Studies: pending. DOI https://doi.org/10.1093/mollus/eyx043
Schilthuizen M., Sipman I., Zwaan J.C. 2017. Sexual dimorphism in shell coloration of Pletostoma (Caenogastropoda: Diplommatinidae) is caused by polyenes. Journal of Molluscan Studies: 1-3.
http://dx.doi.org/10.1093/mollus/eyx043
2016

Journals SCI, peer-reviewed

Zwaan J.C. 2016. Cat’s-eye Väyrynenite from Pakistan. Journal of Gemmology 35 (4) : 288-289.
Zwaan J.C. 2016. Clinohumite from Vietnam. Journal of Gemmology 35 (4) : 279-280.
Zwaan J.C., Pezzotta F., Rossmann G.R. 2016. Orange-Red to Yellowish Brown Cordierite from Madagascar. Journal of Gemmology 35 (1) : 8-9.
Zwaan J.C., Falster A.U., Simmons W.B., Blauwet D. 2016. Tantalite-(Mn) from Grangal, Nuristan, Afghanistan. Journal of Gemmology 35 (2) : 89 p. 111-114.
Zwaan J.C. 2016. Scapolite from Badakhshan, Afghanistan. Journal of Gemmology 35 (4) : 285-287.
2015

Journals SCI, peer-reviewed

Zwaan J.C. 2015. Rhodochrosite from Brazil. Journal of Gemmology 34 (6) : 473-475.
Zwaan J.C. 2015. Purple Tourmaline from Maraca, Mozambique. Journal of Gemmology 34 (8) : 666-667.
Zwaan J.C. 2015. Yellow Scheelite from Khaplu, Pakistan. Journal of Gemmology 34 (4) : 298-299.
Reich S., Warter V., Wesselingh F.P., Zwaan J.C., Laurens L., Renema W. 2015. Paleoecological significance of stable isotope ratios in Miocene tropical shallow marine habitats (Indonesia). Palaios 30 (1) : 53-65. DOI https://doi.org/10.2110/palo.2013.051
Zwaan J.C., Hawthorne F.C. 2015. Tremolite from Mwajanga, Tanzania. Journal of Gemmology 34 (7) : 569-571.
Zwaan J.C. 2015. Stabilized Shattuckite and Bisbeeite from the Democratic Republic of Congo. Journal of Gemmology 34 (8) : 663-666.
Zwaan J.C. 2015. Apatite from Kenya. Journal of Gemmology 34 (4) : 289-290.
Zwaan J.C. 2015. Green Prase Opal from the Kondoa District, Tanzania. Journal of Gemmology 34 (8) : 658-660.
Zwaan J.C., Buter E., Mertz-Kraus R., Kane R.E. 2015. Alluvial Sapphires from Montana: Inclusions, Geochemistry and Indications of a Metasomatic Origin. Gems & Gemology 51 (4) : 370-391. Gemological Institute of America. DOI https://doi.org/10.5741/GEMS.51.4.370.
2014

Chapters in book

Reich S., Warter V., Wesselingh F.P., Zwaan J.C., Lourens L., Renema W. 2014. Paleoecological Significance of Stable Isotope Ratios in Miocene Tropical Shallow Marine Habitats (Indonesia). In: Reich S. (ed.) Utrecht Studies in Earth Sciences. 57: 283-311.

Books as editor

Journals non-SCI, peer-reviewed

Zwaan J.C. 2014. Gem Notes: Blue Kyanite from Tanzania. Journal of Gemmology 34 (3) : 198-200.
Zwaan J.C. 2014. Gem Notes: Green Fluorite from Stak Nala, Pakistan. Journal of Gemmology 34 (3) : 192-194.
Zwaan J.C., Groenenboom P. 2014. Natural pearls from Edible 'True Oysters' in Zeeland, the Netherlands. Journal of Gemmology 34 (2) : 150-155.
Zwaan J.C. 2014. Gem Notes: Bicoloured Grossular from Kambanga, Kenya. Journal of Gemmology 34 (3) : 195-197.
2012

Journals SCI, peer-reviewed

Zwaan J.C., Jacob D.E., Haeger T., Cavalcanti Neto M.T.O., Kanis J. 2012. Emeralds from the Fazenda Bonfim Region, Rio Grande do Norte, Brazil. Gems & Gemology 48 (1) : 2-17. DOI https://doi.org/10.5741/GEMS.48.1.2
2009

Journals non-SCI, peer-reviewed

Zwaan J.C., Dommisse H.A. 2009. A description and history of one of the largest nacreous pearls in the world. Journal of Gemmology 31 (58) : 196-202.
2008

Journals SCI, peer-reviewed

Laurs B.M., Zwaan J.C., Simmons W.B., Falster A.U. 2008. Tourmaline from Muva, Mozambique. Gems & Gemology 44 (3) : 273-275.
Houran J., Laurs B.M., Krzemnicki M.S., Groenenboom P., Kondo D.M., Haenni H.A., Laurs B.M., Hlaing U.T., Win K.K. Fernandes S., Laurs B.M., Zwaan J.C., Koivula J.I., Chadwick K.M., Choudhary G., Overton T.W. 2008. Colored stones and organic materials. Gems & Gemology 44 (3) : 262-281.
Laurs B.M., Zwaan J.C., Breeding C.M., Simmons W.B., Beaton D., Rijsdijk K.F., Befi R., Falster A.U. 2008. Copper-bearing (Paraiba-type) tourmaline from Mozambique. Gems & Gemology 44 (1) : 27 p. 4-30.
2007

Journals SCI, peer-reviewed

Laurs B.M., Zwaan J.C., 2007. Field study on Cu-bearing tourmaline mines in Mozambique. Gems & Gemology 43 (4) : 383-384.
2006

Journals non-SCI, peer-reviewed

Zwaan J.C. 2006. Gemmology, geology and origin of the Sandawana emerald deposits, Zimbabwe. Scripta Geologica 131: 211 p. 1-211. Naturalis, Leiden.
2005

Journals SCI, peer-reviewed

Zwaan J.C., Seifert A.V., Vrana S., Laurs B.M., Anckar B., Simmons W.B.S., Falster A.U., Lustenhouwer W.J., Muhlmeister S., Koivula J.I., Garcia-Guillerminet H. 2005. Emeralds from the Kafubu area, Zambia. Gems & Gemology 41 (2) : 116-148.
2004

Journals non-SCI, peer-reviewed

Seifert A.V., Zacek V., Vrana S., Pecina V., Zacharias J., Zwaan J.C. 2004. Emerald mineralization in the Kafubu area, Zambia. Bulletin of Geosciences 79 (1) : 1-40.

Journals SCI, peer-reviewed

Zwaan J.C., Cheilletz A., Taylor B.E. 2004. Tracing the emerald origin by oxygen isotope data: the case of Sandawana, Zimbabwe. Comptes Rendus Geoscience 336 (1) : 41-48. DOI https://doi.org/10.1016/j.crte.2003.10.015
2003

Journals SCI, peer-reviewed

Donovan S.K., Hoek Ostende L.W.V. van den, Renema W., Vos J. de, Waveren I.M. van, Wesselingh F.P., Prins C.F.W., Zwaan J.C. 2003. Behind the scenes at the Nationaal Natuurhistorisch Museum, Leiden, and the Teyler Museum, Haarlem, The Netherlands: report of a visit by the Geologists' Association, 30 November and 1 December, 2002. Proceedings of the Geologists' Association 114: 279-288.
2000

Journals SCI, peer-reviewed

Calligaro T., Dran J.C., Poirot J.P., Querre G., Salomon J., Zwaan J.C. 2000. PIXE/PIGE characterisation of emeralds using an external micro-beam. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 161: 769-774. DOI https://doi.org/10.1016/S0168-583X(99)00974-X