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

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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)​

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.

The Royal Experience

Royal Coster Diamond is the oldest diamond polishing factory in the world. Since our establishment in 1840, Royals from all over the world came to Amsterdam to see our Amsterdam craftsmanship. We’ve welcomed visitors like Empress Sisi, the Viceroy of China, King Rama V, Prince Napoleon and many, many more.

Today this Royal experience is within your reach. Visit our four monumental 19th century villa's and see how we create beauty that lasts for centuries. We give private guided tours during which your guide vividly tells you about the history of these precious stones and how Amsterdam became the City of Diamonds. You dive into our rich legacy that is filled with Royal Stories. Your guide explains how diamonds are formed and polished, while you see our polishers and goldsmiths up close. You can take a picture of yourself behind a real diamond polishing table and you learn how to analyze a diamond and why some diamonds sparkle more than others. At the end of the tour, you receive a nice goody bag you can use to value your or your family’s diamonds and diamond jewelry.

What do you get?

- A personal guided tour

- Explanation about the 4 C's of diamonds

- Learn about the diamond history of Amsterdam

- See real loose diamonds in all shapes and sizes

- See famous diamond artefacts like the Koh-I-Noor

- See the Royal 201 Patented Collection

Experience Royal Coster

free diamond tour & workshops


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