GT100 gemmology course cover

Start your journey at the source of gemmology: learn about gemstone origins, see how gems are mined and how these extraordinarily valuable minerals get to market. Learn about gemmology quality and value factors for all types of gems, from Diamonds to Coloured Stones, Phenomenal gems, Organics to Jade.

This comprehensive course gives you the knowledge and power to take control of your gem purchases (if you are a collector or enthusiast) or your sales process (if you are a designer or jewellery professional). Beyond the common trade practices, you will see and learn about imitations, synthetics and treatments sometimes used to enhance or even to deceive.

Preview video

Course outline

GT101 Coloured Gems - The Earth's Natural Wonders

GT101 Coloured Gems - The Earth's Natural Wonders

Learn about a variety of beautiful natural minerals and how gemmologists classify them. See how easy it is to identify between different gem types. Discover the attributes of gems versus mere minerals and have revealed the difference between fact and the many misconceptions which abound in this field.
GT102 Factors Affecting the Value of Coloured Gems

GT102 Factors Affecting the Value of Coloured Gems

Unlike diamonds, the 4 C's are weighted differently when applied to coloured gems. Learn methods for evaluating colour in gems and discover how clarity types are assessed. See a wide range of cutting styles available in today’s market and start to learn how to make use of practical jewellers tools of the trade.
GT103 Diamonds, the 4 C's & Beyond

GT103 Diamonds, the 4 C's & Beyond

Colour, Clarity, Cut and Carat are explained from a gemmological point of view. The origins and history of diamonds are reviewed, and an understanding of the modern diamond trade is imparted with useful practical buying tips specific to Diamonds revealed.
GT104 Natural Diamonds, Simulants & Synthetics

GT104 Natural Diamonds, Simulants & Synthetics

Many materials are made to resemble diamonds; some can be easily identified, while others nearly identical. The differences between natural and synthetic diamonds are covered. Tips and quick practical tests are shared to assist in identification. A thorough understanding is gained of differences between Diamond Simulants and Synthetic Diamonds.
GT105 Pearls: Natural, Cultured & Imitation

GT105 Pearls: Natural, Cultured & Imitation

Differences between the varieties of pearls readily available in the market today are identified. Origins of some of the most beautiful specimens as well as common imitations and tests are covered. The Pearl culturing process is fully understood. South sea, Japanese and Chinese pearls are closely inspected.
GT106 Assessing Pearl Value

GT106 Assessing Pearl Value

Varied examples are used to identify the different quality factors of pearls and how they affect price. Colour, lustre, shape, spotting, nacre thickness & make are among factors explained & observed. Tips and tricks for buying Pearls are imparted and how to care for these special gems is closely addressed.
GT107 Phenomenal Gemstones

GT107 Phenomenal Gemstones

Discover an array of special gem materials which react in amazing ways to certain light sources to reveal nine types of gem Phenomena. These range from common varieties to the most rare and expensive of collectors’ items. Natural, Synthetic and Imitations are all handled and view closely.
GT108 Jade and Jade Imitations

GT108 Jade and Jade Imitations

As one of the most popular gems in the Far East, Jade has many imitations, and two genuine forms: Jadeite and Nephrite. Learn about Jade's history and lore. Understand the value factors and selection process. Observe and view first-hand the many imitations available on the market today and see some of the difficulties which arise in mining Jade.
GT109 Organic Gems

GT109 Organic Gems

Materials produced by something living or once living are known as Organic Gems. Amber, Jet, Bone, Ivory, Shell and Coral have been found throughout history in jewellery. Discover what has been done and what opportunities abound with these types of gems and with other, less common but unusual, types found in jewellery today.
GT110 Summary, Testing & Next Steps

GT110 Summary, Testing & Next Steps

A useful review is followed by relevant assessments to ensure all salient points have been understood. Final viewing of Imitations, Synthetics and Assembled gems. Next steps are discussed highlighting the importance and methods of testing with the appropriate testing equipment and techniques.

Student reviews

  • Diamond - Pyramid Shape

    I love the way Tanja teach! The class were never bored as she fills the lessons with examples and stories related to the topic of the lessons.

    - Louis L.(Singapore)


  • Diamond - Pyramid Shape

    Love the history, story and trade sharing by Tanja... Very insightful learning!

    - Eileen L. (Singapore)


  • Diamond - Pyramid Shape

    Loving the gem course and Tanja is always very informative... It's engaging and full of new information

    - Faizal S. (Singapore)


  • Diamond - Pyramid Shape

    Everything was so well organised and executed. There was so much information shared and things to learn that I wish our course was slightly longer.

    - Esther C. (Singapore)


  • Diamond - Pyramid Shape

    Tanja is amazing, professional and really experiece and patient with all of us.

    - Scott P. (Singapore)


  • Diamond - Pyramid Shape

    Great instructor, great course materials and fun environment... I really learn a lot from this course and really love it. I can identify my gemstones better.

    - Su Myat T.


  • Diamond - Pyramid Shape

    Overall, the course was very well planned, course materials were excellent and the instructor was marvellous. I cannot think of a single complaint and I would highly recommend this course to friends who would be interested to know more about the Jewellery and Gem trade. Keep up the good work!

    - Raymond K.


  • Diamond - Pyramid Shape

    I am surprised by the extend of sample gemstones available for use in class. Enough details. Fantastic.

    - Gerard L.


Instructor's profile

  • Tanja, jewellery instructor special portrait

    Tanja Sadow

    Tanja is an award winning jewellery designer & gemmologist with more than 4 decades of experience educating the jewellery industry across 4 continents. Dean and founder of JDMIS, Tanja works with aspiring artisans as well as top jewellery brand team members to help them achieve brilliance in their careers. Read More
  • 1
  • Tools & Materials

    Tools & Materials

    Like all JDMIS courses, students receive everything they need to complete all their coursework. This course includes all the tool and reference material needed in order to fully appreciate the gem exhibits and the jewellery samples.

  • Facilities


    This popular course takes place in our Gem Vault where participants are able to see, examine, scope and understand Tanja's collection of over 1,800 gems, jewellery pieces and examples, including rare and valuable specimens as well as common imitations found in jewellery markets in the region.

  • Learning path

    Learning path

    This course is a Core Component of all learning paths. We refer to these modules as CC.

    Next Step: GT200 - Jewellery Trade Practices 2: Gem Identification Methods.

    Next Step (Complementary Jeweller's Knowledge):
    FT100 - Jewellery Fashion Trends 1: Epic and Contemporary Trends.

    Participants attending and completing this programme as a stand-alone certification can choose to enroll for any full diploma.

  • Duration


    30 hours

    1 week (Full-time), or
    5 weeks (Part-time)

    JDMIS runs weekday & weekend schedules for this popular course. JDMIS also has flexible make-up schedules and graduates can return without cost for refresher courses (subject to availability).

  • Course fee

    Course fee

    SGD 2,020

    Course fee is inclusive of GST as well as all tools and materials provided during the course.

  • 1

Calculate course fees:

Use our easy calculator below to estimate your payable for each training type after using any government funding and SkillsFuture Credits:

What is the method of training you would like to price?
Find out more about the different methods of training at JDMIS here:

What is your residence status in Singapore?

Will your employer be sponsoring your training?

Estimated Fee Payable
This is an estimate of total course fees payable. It is based on the accuracy of information you provided. All grants/SFC payments are subject to SSG approval.

Price represents total course fee payable and is inclusive of tuition, course materials, and GST. SFC claims must be made to SSG 3 days in advance of course start date.

JDMS accepts all major payment methods for payment of jewellery coursesJDMIS accepts Grab Paylater, Atome, and Shopback PaylaterJDMIS accepts all major payment methods, including multiple installment plan services that will allow you to spread your payments in multiple interest-free installments.

Course Gallery

GT100 Gallery Apr21 2
GT100 Gallery Apr21 3
GT100 Gallery Apr21 4
Gem collection 1
Gem collection 2
Gt100 Slider Equipment
Gt100 Gem Students
Gt100 Gem Student Loop
Fundamentals Of Gemmology   Front2 Min
console.log("UTMTracker Running - result: No UTM Data Found");
Troubleshooting Information: