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

Free shipping and insured in Europe.

Lifetime free cleaning and polishing.

Your cart

Your cart is empty

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.

our story

Our Legacy Of 180 Years Of Diamond Craftsmanship

The world’s oldest and most trusted diamond factory has a rich and compelling history. Royal Coster Diamonds is around for a long time, dating back all the way to at least 1840. Actually, Mr. Coster founded his company before that date, but we just cannot prove it. Therefore, we stick to what we do know. Let us tell you more about our eventful history. A few of our highlights are:

Blog posts

Amsterdam; City of Diamonds - Royal Coster Diamonds

Amsterdam; City of Diamonds

By Robert Groot

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...

Read more
Brief History of Diamonds - Royal Coster Diamonds

Brief History of Diamonds

By Robert Groot

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...

Read more
royal experience Royal Coster Diamonds, diamond tour, diamond factory

Visit royal coster

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