Natural certified diamonds: why buy with a certificate
Natural certified diamonds combine lasting value with everyday wearability. The GIA, IGI or HRD gemological certificate independently confirms carat weight, colour, clarity, cut and ethical sourcing — it is the only document that allows you to compare and evaluate exactly what you are buying. One important note: a diamond does not lose value when removed from its original blister pack. It can be freely set into a solitaire ring, a stud earring or any other piece of jewellery without the certificate losing its validity.
How to choose the right diamond
At 18carati you can browse thousands of certified brilliant-cut diamonds from approximately 0.20 ct up to over 10 ct, with prices updated in real time against international market rates. Every stone is laser-inscribed with its certificate number to ensure full traceability. To help you choose, consult our diamond guide: colour, clarity, cut, fluorescence and symmetry explained clearly, so you can find the ideal stone for your budget and taste.
Diamonds and settings: create your bespoke jewel
Once you have chosen your stone, you can pair it with one of the solitaire ring settings we craft by hand in our goldsmith workshop in Arezzo. Your personalised jewel will be ready within a few days, at a price well below what a traditional jeweller would charge — because we work directly as producers with no middlemen. Stone setting is included in the price. We also craft any custom design to the client's drawing: rings, necklaces, earrings and pendants in white, yellow and rose gold 18 carat.
Available cuts: brilliant, princess, heart and more
The selection covers all major cuts: round brilliant, princess, heart, radiant, oval, pear, marquise, asscher and emerald. Use the filters for colour, clarity, cut, fluorescence, symmetry and polish to find exactly the stone you are looking for. If you cannot find what you need or would like advice, contact us directly — our team in Arezzo responds personally, no call centres.
shape
Carat is the weight unit for diamonds. 1.00 carat equals 0.20 grams
Colour
One of the fundamental 4Cs: the less colour a diamond has, the greater its value. The GIA scale runs from D (perfectly colourless) to Z (heavily tinted yellow).
Clarity
Measures the presence of internal inclusions or surface blemishes. The purer the diamond, the more light passes through it and the higher its value.
Cut
Describes how the proportions of a diamond affect its brilliance and light return. It is the most important of the 4Cs. Excellent and Very Good are the best values; Good is acceptable.
IGI, GIA and HRD are the most reliable certificates.
Polish
Describes the quality of finish on the outer surface of the diamond. A high grade maximises light reflection and brilliance.
Symmetry
Evaluates how precisely the facets align and intersect. Minor asymmetries can affect light travel and brilliance. Excellent and Very Good are recommended.
Fluorescence
About one third of natural diamonds emit a completely harmless bluish glow under UV light. Fluorescence rarely affects appearance; in very rare cases it may cause a slight milky effect.