Metals
The metal of a piece determines its colour, weight, durability and care. We always state the metal and, for precious metals, its fineness.
Sterling silver
Sterling silver contains 92.5% silver by weight, marked 925. The remaining metal, usually copper, adds strength. Silver darkens naturally over time as it reacts with sulphur in the air; this tarnish can be removed with a silver cloth.
Gold
Gold is measured in karats (K) or in parts per thousand. Pure gold is too soft for most jewelry, so it is alloyed with other metals.
| Karat | Gold content | Fineness mark |
|---|---|---|
| 24K | about 99.9% | 999 |
| 22K | 91.6% | 916 |
| 18K | 75% | 750 |
| 14K | 58.5% | 585 |
| 10K | 41.7% | 417 |
| 9K | 37.5% | 375 |
Legal minimums for describing an item as gold differ between countries. In Spain, for example, the recognised gold finenesses are 999, 916, 750, 585 and 375. See our Metals Guide.
Colours of gold. Yellow gold is alloyed mainly with silver and copper; rose gold contains a higher proportion of copper; white gold is alloyed with white metals and is often plated with rhodium for a brighter finish that may need renewing over time.
Platinum
Platinum is a dense, naturally white precious metal. Platinum jewelry is commonly 95% platinum (950). It is heavier than gold and does not need rhodium plating to stay white.
Plated and gold-filled metal
Plated jewelry has a thin layer of precious metal over another metal. Gold-filled jewelry has a thicker, mechanically bonded layer. Neither is solid gold, and we never describe them as such.
Diamonds
Natural diamonds
A natural diamond is crystallised carbon formed in the earth. Its quality is usually described with the 4Cs: cut, colour, clarity and carat weight. See the Diamond Guide.
Laboratory-grown diamonds
A laboratory-grown diamond has the same chemical composition and crystal structure as a natural diamond, but it is grown under controlled conditions, by high pressure and high temperature (HPHT) or by chemical vapour deposition (CVD). It is always described as laboratory-grown. See the Lab-Grown Diamond Guide.
Moissanite
Moissanite is silicon carbide. Gem moissanite is created in laboratories because natural moissanite is extremely rare. It is very hard and shows strong fire (flashes of colour). It is a different material from diamond and is never described as diamond. See the Moissanite Guide.
Sapphires and other gemstones
Sapphire is a variety of the mineral corundum, found in blue and in many other colours. Heat treatment to improve colour is common and must be disclosed; a stone can only be described as unheated when a report supports it. The same principle applies to every gemstone we offer.
Natural, laboratory-grown and simulant
| Term | What it means | Example |
|---|---|---|
| Natural | Formed in nature | Natural diamond, natural sapphire |
| Laboratory-grown | Same material as the natural stone, grown by people | Lab-grown diamond, lab-grown sapphire |
| Simulant | A different material that imitates the look of another | Cubic zirconia imitating diamond |
Moissanite is its own material. It is not a laboratory-grown diamond, and it is best described simply as moissanite.
Certificates and treatments
An independent gem report describes one specific stone. It is not a guarantee of value. When a DORVETTI piece comes with a report, its laboratory and number appear on the product page. Read Certificates & Authenticity.
Care
Each material ages differently. Our Jewelry Care guide explains how to clean and store each one safely.
Frequently asked questions
Is sterling silver real silver?
Yes. Sterling silver is an alloy containing 92.5% silver, usually with copper, which makes it more durable than pure silver.
Is a lab-grown diamond a real diamond?
Yes. A laboratory-grown diamond has the same chemical composition and crystal structure as a natural diamond. It must always be described as laboratory-grown.
Is moissanite a diamond?
No. Moissanite is silicon carbide, a different material with its own optical properties. It must never be described as diamond.
What does 18K gold mean?
18 karat gold contains 75% pure gold by weight. The rest is other metals that give strength and colour.
