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Lifetime free cleaning and polishing.

Free resizing service.

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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 Diamond Masterclass Deluxe

This highly exclusive workshop is only for 1 or 2 persons at a time. Your personal guide and master polisher welcomes you to our polishing factory. He or she starts the Masterclass Deluxe with a private tour through the Diamond Museum. The polisher tells you everything there is to know about the origin of diamonds and show you some amazing diamond artefacts. He or she often has some fascinating stories to tell that only true craftsmen know. After the museum tour, you sit down at the polishing table with your polisher. He or she explains about the (protected) craft of diamond polishing and the 4 C’s of diamond valuation. After the explanation, it is time to polish your own diamond.

While you are polishing, the master polisher gives you tips and feedback so you will polish your diamond perfectly. When you are all done, you can keep your diamond as a memento. After the Masterclass Deluxe you see an amazing collection of set and unset diamonds in a private showroom. In the showroom, you can apply your newfound diamond knowledge to these stones. Here you also have the possibility to buy a diamond or a setting for the diamond you just polished. When you completed the workshop successfully, you also receive an official Royal Coster Diamonds certificate.

What do you get?

- Free entrance & guided tour at Diamond Museum

- Personal explanation about diamond polishing & the 4C's

- Polishing a diamond yourself

- Keeping the diamond you polished

- Official Royal Coster Certificate of completion

- See our Royal 201 patented collection

Experience Diamonds at 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