Netherlands Gemmological Laboratory The expertise center for gemstones

Sapphire from Sri Lanka

Everyone who has questions about the nature of gems (natural, synthetic, imitation), their origin, and/or handling can contact us at the Netherlands Gemmological Laboratory. Diamonds are tested for their quality here, too. The Gemmological Laboratory is part of Naturalis.

Don't hesitate to contact us for more information about the services and courses of the Netherlands Gemmological  Laboratory via , or +31 (71) 751 9661.


The Gemmological Laboratory has state-of-the-art equipment. Our experts work at the interface of fundamental and applied research and they respond quickly and competently to questions about gemstones and pearls. Using the vast Naturalis collection, the Netherlands Gemmological Laboratory's work contributes to scientific knowledge about geology and gemstones. Research conducted at the Gemmological Laboratory is published in accordance with internationally recognized standards and guidelines established by the International Mineralogical Association (IMA) and World Jewelery Confederation (CIBJO). This guarantees the consistent and high quality of our specialized work.

Our services

The Netherlands Gemological Laboratory offers the following services to a wide range of clients (including jewelers, goldsmiths, and silversmiths, as well as gemstone and pearl aficionados):

  • Gemstones: identification (including synthetic stones and imitations) and possible handling, investigation into country of origin.
  • Diamonds: grading and investigation into the origin of the color (for fancy color diamonds), investigation into the quality of the weight, color, clarity, and cut.
  • Pearls: identification (including cultured pearls and imitations) and possible handling, determining nacre thickness, and other quality indicators for cultured pearls.

Programs and courses

Interested in becoming an expert on gemstones and pearls? Or would you like to brush up your professional knowledge? The Gemmological Laboratory has interesting programs and courses to offer, complete with professional supervision and state-of-the-art facilities.

More information about our courses, including dates and costs below.

Crown diamonds

and courses

The Netherlands Gemmological Laboratory has been recognized as an "Accredited Teaching Centre" by the London-based Gem-A since 2013. We are certified to offer the Foundation in Gemmology and Diploma in Gemmology programs. Once you have earned your diploma in Gemmology, you may apply to be a Fellow of the Gemmological Association of Great Britain, which will entitle you to use the internationally recognized letters "FGA" after your name. We also offer courses for professionals and the general public.

Gemmologist programs

Enrolling in a program at the Netherlands Gemmological Laboratory means gaining professional knowledge under the guidance of the best experts, using outstanding facilities. Certified according to the strict standards of the renowned Gemmological Association of Great Britain (Gem-A), our programs meet the highest international requirements. The Gemmological Laboratory offers the following programs.

Foundation in Gemmology

This introductory program covers basic gemology and is essential for the Diploma in Gemmology program. In Great Britain, Gem-A’s Foundation in Gemmology has Level 4 accreditation, making it an authentic Certificate of Higher Education.

  • Start: 17 January 2022 (exams in June 2022)
  • Frequency: every other week on Monday or Tuesday
  • Time: 9:30am - 4:30pm
  • Cost: €3,225
  • Location: Netherlands Gemmological Laboratory, Darwinweg 2, Leiden

Diploma in Gemmology

As a graduate of this program, you will have a solid training in gemology and may apply to be a Fellow of the Gemmological Association of Great Britain, which will entitle you to use the internationally recognized letters "FGA" after your name. In 2012, Gem-A’s Diploma in Gemmology was assessed as a "Level 6" qualification in the UK, which is the equivalent of a Bachelor of Science (BSc) degree.

  • Start: Monday, October 4, 2021 (exams in June 2022)
  • Frequency: every other weeks on Monday
  • Time: 9:30am - 4:30pm
  • Cost: €4,800 (€4,950 after other preliminary training, such as FEEG, etc.)
  • Location: Netherlands Gemmological Laboratory, Darwinweg 2 , Leiden

The cost includes course materials (including textbook and a foundation instrument kit containing a magnifying glass (10x), tweezers, cleaning cloth, spectroscope, dichroscope, folding polariscope and conoscope, Chelsea color filter, and various lights), and admission to the exam in Leiden; does not include VAT (if you register as a company, you can apply to reclaim the VAT).

The gemmology programs are taught in English.

More information about the programs offered by the Netherlands Gemmological Laboratory:


Are you interested in one of the above programs? You can register by filling out this form this form and sending it to

Gemmology courses

Using our specialist facilities and supervised by the best experts, the Netherlands Gemmology Laboratory offers the following courses.

Practical Gemmology

The Netherlands Gemmology Laboratory offers the four-day Practical Gemmology course for people who are starting out as jewelers or want a solid grounding of practical knowledge about gemstones. In a few short days, the course covers the gemstones (natural, synthetic, imitation) and pearls that are available on the market.

Participants are provided practical tools to recognize the most common gems and pearls. This offers a unique opportunity to practice extensively with the requisite tools under professional supervision.

The Practical Gemmology course does not require special training and participants receive a certificate as proof of participation at the end.

  • Length: 4 days
  • Time: daily, 9:30am - 4:30pm
  • Date: dates for 2021 are to be announced.
  • The four-day course costs €589 (excl. 21% VAT), includes course materials and use of the instruments on site. Lunch is not included in the price.
  • Location: Netherlands Gemmological Laboratory Oortweg 19, Biopartner 2 building, Leiden


Register for the Practical Gemmology course by sending an email to Please include your name, address, email address, and telephone number. As soon as enough participants register (5 minimum, 8 maximum), and at least two weeks before the start of the course, we will contact you to set the exact dates.

Grown diamonds

Gemmology Refresher Class

Designed especially for professionals (such as jewelers and goldsmiths and silversmiths) who work extensively with gemstones, the Netherlands Gemmology Laboratory offers a one-day refresher class. Our experts bring participants up to speed on the latest developments in the field and you can try out the latest techniques yourself.

It can be difficult to tell real from fake. Where are your limitations in this regard? In this refresher course we show you the latest handling methods for gems to keep you current in this area. With an emphasis on diamonds, rubies, emeralds, and sapphires, you'll test your professional skills to find out when you can identify a synthetic product, and when not. That way, you'll know in which cases you should turn to a specialist laboratory like ours.

Special master classes

Gemmology Laboratory clients may be interested in learning more about a particular topic. For them, we offer special master classes. If desired, the laboratory can organize a master class for a private group. This assures you optimal guidance, tailored to your needs. The Gemmology Refresher Class requires basic knowledge of gemology or prior gemmology training, such as FGA or FEEG.

  • Length: 1 day
  • Time: 9:30am - 4:30pm
  • Date: to be announced.
  • Location: Netherlands Gemological Laboratory, Darwinweg 2, Leiden
  • Costs: the one-day Gemmology Refresher Class costs €180 (excl. 21% VAT), includes course materials and the use of the instruments on site. Lunch is not included in the price.


Register for the Gemmology Refresher Class by sending an email to Please include your name, address, email address, and telephone number.

The Netherlands Gemmological Laboratory is part of Naturalis Biodiversity Center

PO Box 9517
2300 RA Leiden
telephone +31 (71) 751 9687 en +31 (71) 751 9661