The world of gemstones offers such an endless choice of colour and variety of fascinating minerals that they can satisfy even the most difficult of people to please. Since the dawn of history, men have put their lives at risk in the search for the most beautiful, naturally created, specimens from earth.

What you will learn

  • The 4Cs of gems

    The 4Cs of gems

    Learn how the 4Cs: colour, cut, clarity and carat weight affect the values of different gems in the market.
  • Facts about diamonds

    Facts about diamonds

    Colourless diamonds are perhaps the most popular gemstone - learn how the 4Cs apply specifically to this unique gem.
  • Appreciating Coloured Gems

    Appreciating Coloured Gems

    Learn how coloured gems are classified and how to best appreciate their rare properties.
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Instructors' profile

  • Tanja Sadow

    Tanja Sadow

    Tanja is an award winning jewellery designer with more than 3 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
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A message from Tanja


What our students have to say?

  • The instructors at JDMIS are professional and well educated.

    - Marie K. (Sweden)

  • Excellent! I enjoyed this immensely. Time whizzed past without me realizing it!. I would most definitely tell my friends about JDMIS and I hope to come back and attend more courses in the near future.

    - C.R. (Brazil)

  • I totally would tell a friend to come to JDMIS. I loved the course in general.

    - PJ (Singapore)

  • The instructors at JDMIS are very professional and provide good quality materials.

    - Yvonne M. (Germany)

  • JDMIS is the only school where you can learn professional techniques in jewellery making. Ms. Tanja Sadow is a great teacher and one can feel very comfortable with her and it's great fun in class.

    - N.B. (France))

  • I would tell people about the how professional the instructors at JDMIS are as well as the crafts and skills offered for upgrading

    - Dennis.W. (Singapore)

  • The lessons and materials at JDMIS are well prepared.

    - J.T. (Singapore)

Kindly sign up below to gain instant access to this exclusive webinar, for free!

In this 45-minute instant webinar recording, you will learn Coloured Gems classifications and the fundamental 4C of Gems: Cut, Colour, Clarity and Carat Weight of Gems and Diamonds.

Learn this essential knowledge from JDMIS' Dean and Founder, Tanja Sadow, who has more than 30 years of experience in the industry.

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