At the heart of it since 1840.

At the heart of it. Since 1840.

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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.
Our 8 Diamond Guarantees - Royal Coster Diamonds

Our 8 Diamond Guarantees

Royal Coster Diamonds is the best choice for a reason. Not only does our long and rich history tells you that you can trust your jewelry with us. But Royal Coster also wants to provide you with certainty in every area when you purchase something as valuable as a diamond. Therefore we’ve created our 8 diamond guarantees.

#1 More than 180 years of craftsmanship

Our company was founded in 1840. Since then we created the most beautiful jewelry and polished some of the most valuable diamonds ever. With over 180 years of craftsmanship, you can certainly trust us with your jewelry as well.

#2 Lifetime diamond upgrades

We love to see a diamond ring passed on for generations. Therefore we reimburse 100% of the price you paid when you bought the ring if you want to upgrade the diamond in it.

#3 Personal and honest advice

Diamonds come in different shapes, sizes, colors, and quality. To select the perfect diamond that fits your personal taste We have more than 150 diamond consultants who offer customized advice in over 35 languages.

#4 Knowledge is everything

One of the most important diamond guarantees is transparency regarding diamond knowledge. We are well aware that purchasing diamond jewelry is a serious matter. In order to let you make an informed decision, we give you a thorough insight into the 4 C’s of diamond valuation. At Royal Coster, we want you to get the best value for your money. That is also why we provide (free) guided tours to learn everything about diamonds.

placing diamond in setting

#5 Only the finest quality diamonds

Our diamond polishers are the best in the business. They have a passion for perfection and extraordinary craftsmanship. Therefore, they turn every rough diamond into a beautiful piece of jewelry that lasts for centuries.

#6 Straight from the source

We have the largest stock of diamonds in Europe. We get our rough diamonds straight from the source, so no middleman is involved. That’s why we can offer you the best price for your diamonds.

#7 Honest and responsible diamonds

We trace all our purchased diamonds directly back to their source. This makes sure that we stay far away from conflict or ‘blood’ diamonds.

#8 Only the highest standard of Diamond certification

We have certifications for all of our diamonds such as the HRD, IGI, GIA or Royal Coster.

Need more affirmation than these diamond guarantees? Discover our stunning Royal 201 collection and see why we have the most beautiful diamond jewelry!

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