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Find Your Ring Size

Royal Coster
Diamonds Size
MM / INCH (Circumference)
48 / 1.89 48 4½ 8
49 / 1.93 49 9
50 / 1.97 50 K 10
51 / 2.01 51 L 11
52 / 2.05 52 6 12
53 / 2.09 53 13
54 / 2.13 54 14
55 / 2.17 55 O 15
56 / 2.20 56 P 16
57 / 2.24 57 8 17
58 / 2.28 58 18
59 / 2.31 59 R 19
60 / 2.36 60 9 S 20

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Diamond Masterclass

Become a true expert

  • An exclusive 4-hour workshop for a maximum of 2 participants at a time.
  • Private tour of the Diamond Museum
  • Polishing your very own diamond under the expert guidance of a skilled diamond polisher
  • Beverages and a gift
  • The Diamond masterclass Polishing Certificate
  • Free consultation with the diamond advisors on setting your diamond (optional)

To book this exclusive experience, please get in touch.

Experience Diamonds at royal coster


Curious how the hardest material in the world is cut into a beautifully sparkling diamond? No better way than experiencing it yourself!

After this highly exclusive workshop (max 2 persons at a time) you will master the skill of cutting diamonds. Your personal guide/master polisher will welcome you to our polishing factory in the centre of Amsterdam. Before the workshop starts, he or she will take you on a private tour through the Diamond Museum and tell you everything there is to know about the origin of diamonds. You will also see some amazing diamond artefacts, and our master polisher will tell some fascinating stories only true craftsmen know.

After the museum, it’s time to sit down at the polishing table. Cutting diamonds requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty. So, before we start our diamond polisher explains everything about the (protected) craft of diamond polishing and the 4 C’s of diamond valuation.

After the extensive explanation, it is time to start polishing your own diamond. To make sure you will polish your diamond perfectly, you will be given clear instructions, tips, and feedback during the polishing. When your personally cut diamond is finished, you will receive your official Royal Coster Diamonds polishing certificate.

But we are not finished yet! After the masterclass you will be treated with an amazing collection of set and unset diamonds in one of our private showrooms. Here you will also get the opportunity to acquire a setting for the diamond you've personally cut and craft it into a one-of-a-kind jewelry.

Want to have the chance to polish your own diamond? Book your Diamond Masterclass today.

free diamond tour & workshops

visit royal coster

Book an experience and learn about our heritage or visit us to see more diamonds & jewelry