Lifetime free cleaning and polishing service.

Free insured shipping in Europe.

Your cart

Your cart is empty

Bekijk deze collecties.

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

Discover your ring size

Measure an existing ring Measure your finger

Your Enquiry

Your Enquiry




A Family Visit - Royal Coster Diamonds

A Family Visit

The Royal Coster Family

But who is the Royal Coster Family? Of course, many members of our ever-expanding family are customers. Our colleagues are also proud members. But also former colleagues are still part of our inner-circle. No matter how long it has been, family is always welcome. That’s why every now and then we are visited by former colleagues. One of them is Theo (84).


For 67 years, Theo was a diamond polisher. He worked here at Coster until he was 80(!) years old. Theo is the embodiment of Coster: super friendly, kind, always happy and helpful to colleagues and visitors alike. He always chatted with clients, gave explanations in both Dutch and German. And he also did group tours in the Diamond Museum next-door. Theo behind the polishing tableTheo was ready to take place behind the polishing table again.

A visit to Coster

A few days ago, Theo and his son-in-law Gerard dropped by. They just paid a visit to the Rijksmuseum and Theo insisted they would drop by at Coster. Sneaking silently into the company canteen, it didn’t take long before colleagues recognized Theo. After all, many of us worked with him. After greeting some familiar faces, Theo revealed the reason for his unannounced visit: his son-in-law needed to learn about diamonds! And who better to do so than Theo himself? There’s no way back now, Gerard. Theo and MamadouA lot of colleagues still know Theo (left). Mamadou (right) and he polished together for many years.

The shoe still fits

Before we knew it, Theo was standing next to one of the polishing stations. He explained the diamond polishing process like a pro. It looked as if he never left. Theo showed Gerard what it takes to turn a rough diamond into a sparkling brilliant. And why the 4 C’s of diamond valuation are so important and determine the gem’s value. Like a true craftsman, of course, Theo couldn’t resist the chance of sitting behind a polishing desk again. But also his son-in-law got the opportunity to feel like a true diamond polisher. Gerard and Theo behind polishing tableGerard (left) gets a private lesson from his father-in-law.

Family is always welcome

Overall, it was quite an exciting day. It was nice to see Theo again. As a member of our family, you are always welcome, announced or unannounced. But if you let us know next time, we’ll make sure the coffee is hot and the champagne is on ice. See you next time!


Do you want to learn more about diamonds and see what Theo loves so much about Royal Coster Diamonds? Discover more during one of our diamond tours.
Previous post
Next post