Order before Feb. 10th and get it before Valentine's.

Free shipping and insured in Europe.

Lifetime free cleaning and polishing.

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Why not explore our new Luna Collection?

Find Your Ring Size

Royal Coster
Diamonds Size
Internal Diameter / Circumference (mm)​
14,01
14,33
14,65
14,97
15,21
15,61
15,92
16,24
16,56
16,88
17,20
17,52
17,83
18,15
18,47
18,79
19,11

How To Measure

The Hands-on Method​ Measure an Existing Ring
  • 1. Grab a tape measure, length of string or strip of paper.
  • 2. 2. Wrap one of these objects around your finger. Mark the place where the two end of the measuring object come together.
  • 3. When using string or paper grab a ruler. Lay it on a flat surface and measure to where the marked point is.
  • 4. Use the chart presented above to acquire the correct ring size.

Discover your love

Royal Coster Diamonds

With nearly 200 years of experience, we are experts in diamond cutting. We have created jewelry for Prince Napoleon, for Empress Sisi and in 1852, the craftsmen of Royal Coster were chosen by Queen Victoria to re-polish the largest diamond in the world; the Koh-I-Noor. Located on the Museumplein in Amsterdam, we are at your service for diamond jewelry, high-end watches, tours and workshops. 

the new

Royal 201 signature c collection

tennis collection, timeless, elegant and beautiful, tennis bracelet, tennis necklace

Tennis Collection

Timeless, elegant and beautiful

rainbow collection, rainbow jewelry, colour diamonds, rings, necklace, bracelet
rainbow collection, rainbow jewelry, colour diamonds, rings, necklace, bracelet

Rainbow Collection

All the colors of the rainbow are the foundation of our unique Rainbow Collection

Our best selling watch collections

Our watch boutique has the best brands in Haute Horlogerie.

diamond crafting ideas

Design your own ring

Send a sketch of your own design and let our goldsmiths fulfill your wish

Share our knowledge

Learn more about the magic of diamonds

Amsterdam; City of Diamonds - Royal Coster Diamonds

Amsterdam; City of Diamonds

How did Amsterdam become the City of Diamonds? Amsterdam has been the City of Diamonds for more than 400 years. The story of how Amsterdam became the diamond capital of...

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Brief History of Diamonds - Royal Coster Diamonds

Brief History of Diamonds

In the hectic days of constant rushing around, the little sparkle of a diamond helps you pause for a second and forget about the worries of the world. Take that...

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free diamond tour & workshops
free diamond tour & workshops

Visit Royal Coster

Book An Experience And Learn About Our Heritage Or Visit Us To See More Diamonds & Jewelry