Gem Studies Laboratory (GSL) in Sydney is the Gemmological Association of Australia’s endorsed diamond grading laboratory.

GSL (Gem Studies Laboratory) was started over twenty years ago to meet the demand in Australia for a first-rate diamond laboratory. Today it has become the best known independent diamond certification and gem identification laboratory in Australia.

Over the years that GSL has been in business we have identified and valued countless diamonds and coloured gemstones, issued hundreds of opal and coloured stone certificates and tens of thousands of diamond certificates.

The Complete Gem Testing Laboratory

With our genuine commitment to the Australian gem and jewellery industry, and our to desire to improve and enrich it, we have access to the latest equipment and the most sophisticated instruments that allow us to offer a wide range of services to our clients. These include;

  • Diamond Certification
  • Diamond Fingerprinting
  • Pearl X-ray Testing
  • Gemstone Authentication
  • Gem & Jewellery Photography
  • GSL’s Australian Opal and Gemstone Photographic Library

Experience and Commitment

Our clients come to us for our experience and qualifications, but most importantly for our commitment to customer service. In the last five years we have received two Australian Achiever Awards – for the overall operation of our laboratory and our Australian Opal and Gemstone Photographic Library.

Jewellery retailers, manufacturers, and wholesalers all use the services provided by GSL, along with diamond and gemstone importers, Australian Customs, the NSW and Federal Police Forces, the Department of Public Prosecutions, antique dealers and Australia’s foremost auction houses.

The people who bring their valuable gems to GSL come for the certainty. We take our client’s trust very seriously and have built our reputation on it.

Recording Australia’s Gemstones

Earning national recognition in 2001, the Australian Opal and Gemstone Photographic Library was started with the realisation that as many as 95 per cent of Australia’s best opals end up overseas. It now documents some of the finest gemstones and opals in Australia and offers future generations the chance to access a fantastic visual reference of Australia’s opal and gemstone history. The images are widely used in both Australian and international publications.

Our Partnership with the GAA

In 2003 GSL and GAA (the Gemmological Association of Australia) formed an historic alliance as part of our ongoing commitment to the Australian gem and jewellery industry. GAA’s endorsement of GSL as its diamond certification and gem testing laboratory ensures that our facilities meet the highest standards and that all techniques and equipment used in our laboratory are state-of-the-art and in line with the latest international standards. When you come to GSL you are guaranteed the best service available from the best team in the business!



Bill Sechos

With over twenty five years’ experience, Bill holds a science degree from the University of Sydney and received the Australian Prize for his achievements whilst completing the GAA Diploma of Gemmology. He has served as the GAA president and chairman of the GAA Board of Studies and Examinations. Bill is actively involved with their training programmes as senior lecturer.


Rudy Weber

At age 15 Rudy was already helping his father find, cut and polish gems. He trained to become a licensed diamond grader with the Diamond Grading Laboratory in London, where he met Bill and the GSL partnership was formed. With a love of photography, Rudy set up GSL’s unique Australian Opal and Gemstone Photographic Library.


Flora Theodore

GAA-trained in diamonds, Flora has been working with GSL as a diamond grader since 1996. With her love of gemmology and her commitment to clients, Flora is an essential member of the GSL team.

Contact Gem Studies Laboratory

Phone: (02) 9264 8788
Fax: (02) 9267 8556
email: info@gsl.net.au
web: gemstudieslaboratory.com.au