GIA
Gemological Institute of America
The strictest and most widely recognised diamond grading standard, especially for natural stones.
Verify a reportDiamond wholesale · Zagreb
Certifieddiamonds and finegemstones
A natural diamond travels a long way: from a crystal mined deep in the Earth, through planning and precise cutting, to independent grading by GIA, IGI or HRD. A lab-grown diamond forms under controlled conditions. We label and document both clearly.
TableThe largest flat facet on top. Light enters the diamond through it.
- Table: The largest flat facet on top. Light enters the diamond through it.
- Crown: The upper part above the girdle. Its facets split light into colours.
- Girdle: The widest edge of the diamond, between crown and pavilion. It often carries the laser inscribed report number.
- Pavilion: The lower, cone shaped part. The right angle sends light back to the eye.
- Culet: The bottom point of the diamond, pointed or slightly polished.
What we do
Four areas, one standard
Every stone comes with a clearly stated origin and an independent certificate.
01
Natural diamonds
Formed in the Earth billions of years ago, graded by GIA, IGI and HRD.
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02
Lab-grown diamonds
The same diamond, grown by CVD or HPHT. The method is always stated.
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03
Gemstones
Sapphires, rubies, emeralds and other gemstones with stated origin.
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04
Custom jewellery
From sketch and 3D model to the finished piece in white, yellow or rose gold.
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Transparency
From rough crystal to certified stone
Natural and lab-grown diamonds look identical to the naked eye. That is why we never leave origin to impression: it is written on the documents and the certificate.
We source natural diamonds only from legitimate suppliers, in line with the Kimberley Process and the System of Warranties.
- Tradition
- Since 1987
- Based in
- Zagreb
- Certificates
- GIA · IGI · HRD
- Partners
- Croatia, region, EU
Cut and light
The cut decides how much light a diamond returns.
The world of gemstones
Colour, shape and character of every stone
Certificates
Independent grading you can verify
We work with three laboratories whose reports are accepted by the trade worldwide.
IGI
International Gemological Institute
The most common report for lab-grown diamonds, stating the growth method.
Verify a reportHRD
HRD Antwerp
A European laboratory in Antwerp with a long tradition in diamond grading.
HRD Antwerp
Custom jewellery
From idea to finished piece
Engagement rings, wedding bands and one of a kind pieces. Before production you receive a precise 3D render, and you choose the stone with expert advice.
Wholesale
A reliable partner for jewellers
We supply jewellers, retailers and manufacturers with certified diamonds and gemstones on a regular basis, to their exact specifications.
FAQ
About us and our work
What does CT Direct do?
We are wholesalers of natural and lab-grown diamonds and natural gemstones, and we make custom jewellery. We work with jewellers, designers and private clients.
What is the difference between a natural and a lab-grown diamond?
Chemically, physically and optically there is none: both are pure carbon with a hardness of 10. They differ in origin and price. The origin is always stated on the documents and the certificate.
Which certificate comes with a diamond?
A report from an independent laboratory: GIA, IGI or HRD. The report number can be checked directly on the laboratory website.
Do you work with private clients?
Yes, for choosing a certified stone and for custom jewellery, most often engagement rings. Jewellers and companies can work with us on wholesale terms.
Contact
Let us talk
For questions about diamonds, gemstones, a partnership or custom jewellery, get in touch directly. We will be glad to help.
- +385 95 3632 282Phone and WhatsApp
- info@ctd.hr
- Zagreb, Croatia