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Gemmata N.V.

Established 1982, Rio Tinto Diamonds Customer Since 1994

Established in 1982, Gemmata nv is a very diversified company. It is specialized in industrial diamonds, but trades rough and polished diamonds as well. Furthermore, Gemmata owns the jewellery brand Casa Gi.

Products & Services

Gemmata’s main focus is industrial diamonds. Its extensive industrial assortment includes cubes, dies, dresser, flat shapes, flats, longs, maccles, round shapes, sawn 2p and sawn 4p.

Gemmata’s jewellery brand, Casa Gi, stands for luxury and quality. It manufactures 18 carat golden deluxe jewellery, set with diamonds of the highest quality, sometimes in combination with other materials such as jade and lava but always with a touch of imagination.


For many years now, Gemmata has been very well positioned worldwide. Today its core focus is the Chinese market, where it is continuously expanding its activities. The main Chinese office, Hewei Diamond Trading Company in Shanghai, runs a jewellery factory in Panyu and a wholesale jewellery store in Shenzhen.

Vision & Strategy

Gemmata is and wants to remain a world leader in industrial diamonds. However, it can also rely on its great knowhow on trading rough and polished diamonds.
Gemmata’s objective is to increase its business in China and to expand its jewellery brand, Casa Gi, around the world.

Company/Family Background

Since 1982 Jan Leemans successfully runs Gemmata nv. A few years ago, his two sons, Stefan and Dennis, joined and reinforced the authentic family business.

 Business Offerings 
  • Rough Dealer
  • Cutting & Polishing
  • Polished Sales
  • Jewellery Manufacturing
  • Jewellery Sales

 Product Range  Core Products
Rough / Industrial
Product Brands
Casa Gi (jewellery)

 Sales Regions 
  • Belgium
  • China
  • India

  • Argyle
  • Diavik

 Principal(s)/Founder(s)  Jan Leemans
Director/General Manager

 Contact Information  HEAD OFFICE
Gemmata N.V.
Hoveniersstraat 2
Box 539
2018 Antwerp
T: +32 3 222 4080
T: +32 3 233 8973
F: +32 3 232 9822

Casa Gi International
Stefan Leemans
Hoveniersstraat 2 Box 530
2018 Antwerp
T: +32 3 231 3068
F: +32 3 232 4914

Boo-Bijou BVBA
Stefan Leemans
Address: Hoveniersstraat 2 Box 530
2018 Antwerp
T: +32 478 62 87 48

Hewei Diamond Trading Co. Ltd.
Mr. Yu
Room 418
Nr 270 CAO XI Road
200235 Shanghai
T: +86 21 6451 5546
T: +86 21 6451 5675 1-8
F: +86 21 6451 5523