Understandingdiamonds
Four criteria determine the value of a diamond, one its radiance. This guide explains the 4Cs, clarity grades, price, authenticity and colour, clearly and without detours.
The value of a diamond looks like a riddle, yet it is clearly regulated.
Four criteria, known internationally as the 4Cs, describe it completely: cut, colour, clarity and weight. Whoever reads them understands why two stones of the same size can lie far apart in price, and what really matters when buying.
The 4Cs: cut, colour, clarity, carat
The 4Cs are the international vocabulary for diamond quality. Each of the four criteria describes a property of its own, and only together do they make up the value of a stone.
- Cut: determines the radiance, the only one of the four criteria determined by people.
- Colour: for white diamonds ranges from D (colourless) to Z (tinted).
- Clarity: describes how visible natural inclusions are.
- Carat: one carat equals 0.2 grams, the price rises disproportionately.
Clarity and clarity grades
Almost every diamond carries tiny inclusions, traces of its growth. The clarity grade describes how visible they are. Decisive for the effect is the point from which a stone is eye-clean.
- FL / IF
- Flawless. No inclusions can be found under tenfold magnification.
- VVS1 / VVS2
- Very, very small inclusions, hard to detect even under the loupe.
- VS1 / VS2
- Very small inclusions, not visible to the naked eye (eye-clean).
- SI1 / SI2
- Small inclusions, clearly recognisable under the loupe.
- I1 to I3
- Inclusions, some of which are visible to the naked eye.
In practice this means: from VS a diamond is clean to the eye, without the premium of the highest grades.
Diamond or brilliant?
Diamond denotes the material, brilliant the cut. A brilliant is a diamond in the round cut with 57 facets, calculated for maximum light return. So every brilliant is a diamond, but not every diamond is a brilliant.
In depth: the difference→What a diamond costs
The price results from all 4Cs together, not from the weight alone. Because large rough stones are rare, the price per carat rises disproportionately: a stone of one carat costs considerably more than two stones of half a carat each.
For the effect it pays not to neglect the cut. An excellently cut stone looks livelier than a larger but dully cut one. At Diamonds in Glass prices are quoted individually, as every piece is calculated according to the properties of its stone.
Authenticity and certificate
The most reliable way to recognise a real diamond is a certificate from an independent laboratory. Home tests such as the fog test or checking the refraction give clues but do not replace a gemmological examination. Every Diamonds in Glass piece is delivered with a certificate number.
In depth: recognising authenticity→Colour and fancy colours
For white diamonds the rule is: the less colour, the rarer and more valuable, measured on the scale from D to Z. Fancy colour diamonds follow the opposite logic. Champagne, yellow, pink or blue are real diamonds whose colour increases the value instead of reducing it.
In depth: the rare colours→The diamond in glass
Diamonds in Glass holds the diamond in glass instead of metal. The stone stays real, documented and untouched in its value. The glass acts like a lens, makes it visible from 360 degrees and lets it appear deeper and larger.
Frequently asked questions
Answered briefly
The 4Cs are cut, colour, clarity and carat (weight). They describe the quality and together determine the value of a diamond.
From VS1 and VS2 inclusions are no longer visible to the naked eye and the stone looks perfectly clean. VVS and IF are rarer and more expensive, but the optical difference is hardly perceptible to the eye.
The price depends on all 4Cs and varies greatly. Two one-carat stones can differ in price many times over, depending on cut, colour and clarity. Carat weight alone says little about the price.
Diamond denotes the material, brilliant the cut. A brilliant is a diamond in the round cut with 57 facets. Every brilliant is a diamond, but not every diamond is a brilliant.
Most reliably via a certificate from an independent gemmological laboratory. Home tests such as the fog test give clues but do not provide a certain verdict.
A real diamond with natural colour, such as champagne, yellow or blue. Unlike with white diamonds, colour increases the value here instead of reducing it.