Lifetime free cleaning and polishing service.

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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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luxury shopping experience



  • Free guided 30 minute tour available in 25 languages
  • Visit the oldest operating diamond polishing factory
  • See the The Royal 201 diamond, replica of Koh-I-Noor, and extensive diamond collections.
  • Enjoy Tax-free shopping options

Explore the oldest diamond factory

Ready for a fascinating new experience? As the oldest, still operating, diamond polishing factory in the world, we invite you to step into the magical world of diamonds right here in our factory in Amsterdam. During the free guided tour, we will share our knowledge and show you the rich history and many facets of diamond cutting techniques, from the rough diamond to the sparkling end result. Of course, you'll also be given the opportunity to buy diamonds, provided with personal advice from our team of experts.

Our experienced guides will tell you everything about the origins of diamonds, if available in your own language. You will see with your own eyes how our master polishers cut and polish the rough stones into well balanced diamonds. You will become acquainted with the various stages and types of ‘cut’ and the many other facets of this fascinating craftsmanship.

But there is so much more to experience! We will show you our masterpiece: The Royal 201. This is our own patented diamond, known to have the most exciting sparkle in the world. To complete your tour, you will see an exact replica of the famous Koh-I-Noor and a display of the British Crown Jewels. Did you know we have one of the largest collections of unset diamonds in the world? So, book your free visit now and experience the fascinating world of diamonds!

Experience royal coster

free diamond tour & workshops

Visit royal coster

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