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Find Your Ring Size

Royal Coster
Diamonds Size
MM / INCH (Circumference)
48 / 1.89 48 4½ 8
49 / 1.93 49 9
50 / 1.97 50 K 10
51 / 2.01 51 L 11
52 / 2.05 52 6 12
53 / 2.09 53 13
54 / 2.13 54 14
55 / 2.17 55 O 15
56 / 2.20 56 P 16
57 / 2.24 57 8 17
58 / 2.28 58 18
59 / 2.31 59 R 19
60 / 2.36 60 9 S 20

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Canals of Amsterdam

Inspired by the city of Amsterdam

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. 

Rainbow Ring

Shines brighter than the rainbow

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Mystical world of diamond craftmanship

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Learn more about the magic of diamonds

Amsterdam; City of Diamonds - Royal Coster Diamonds

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Brief History of Diamonds - Royal Coster Diamonds

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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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