1. Cut: the source of sparkle
Cut is the only C shaped entirely by human hands. It describes the proportions, symmetry and polish of a diamond, and it decides how much light comes back to your eye. A well-cut diamond acts like a hall of mirrors: light enters through the top, bounces between the facets and returns as brightness, colour and sparkle. If the stone is cut too deep or too shallow, light escapes through the bottom and the diamond looks dull, even when its colour and clarity are excellent.
Laboratories grade the cut of round brilliant diamonds on a five-step scale. For fancy shapes such as oval, pear or emerald, the grading focuses on polish and symmetry, and an experienced eye judges the overall light performance.
| Cut grade | What it means |
|---|---|
| Excellent / Ideal | Maximum brightness, fire and sparkle. The standard we work with. |
| Very Good | Very bright; small differences only visible side by side. |
| Good | Reflects most light, but noticeably less lively. |
| Fair | Light leaks out; the diamond can look glassy. |
| Poor | Dark areas and little sparkle. |
Our advice: never compromise on cut. An excellent cut makes a diamond look brighter, whiter and even larger than a poorly cut stone of the same weight.
2. Colour: the purity of white
The finest diamonds are completely colourless, like a drop of pure water. Most diamonds show a slight yellow or brown tint caused by traces of nitrogen or other elements. The colour scale runs from D (colourless) to Z (light yellow). Differences between neighbouring grades are so subtle that gemmologists compare stones against master sets under controlled light.
| Grade | Category | Appearance |
|---|---|---|
| D, E, F | Colourless | Icy white, no visible tint. D is the rarest grade. |
| G, H, I, J | Near colourless | A faint warmth visible only when compared. |
| K, L, M | Faint | A noticeable warm tint. |
| N to R | Very light | Clearly yellowish. |
| S to Z | Light | Distinct yellow or brown colour. |
Every BEUSÉA centre diamond is graded D colour, the highest grade on the scale. It stays bright white in every metal and every light, whether it is set in white gold, platinum or warm yellow gold.
3. Clarity: nature's fingerprints
As diamonds grow, tiny crystals, feathers or clouds can form inside them (inclusions), and small marks can appear on the surface (blemishes). Clarity describes their number, size, position and visibility under 10× magnification. Most are invisible to the naked eye, but they can affect how light travels through the stone.
| Grade | Name | Under 10× magnification |
|---|---|---|
| FL | Flawless | No inclusions or blemishes. |
| IF | Internally Flawless | No inclusions, only tiny surface details. |
| VVS1, VVS2 | Very, very slightly included | Minute traces, extremely hard to find even for experts. |
| VS1, VS2 | Very slightly included | Small traces, difficult to see under magnification. |
| SI1, SI2 | Slightly included | Noticeable under magnification, sometimes visible to the eye. |
| I1, I2, I3 | Included | Obvious inclusions that can affect beauty and durability. |
We select centre diamonds from VVS1 to VS1. They are completely clean to the naked eye and sit in the range where clarity no longer changes what you see, only what a microscope sees.
4. Carat: weight, not size
Carat is a unit of weight: one carat equals 0.2 grams and is divided into 100 points, so a 0.50 carat diamond is often called a "fifty pointer". Because larger rough diamonds are rarer, price rises faster than weight. The diameter grows more slowly than the weight: a 2 carat round diamond is not twice as wide as a 1 carat stone.
| Carat weight | Approx. diameter (round) | Approx. size (oval) |
|---|---|---|
| 0.50 ct | 5.1 mm | 6.0 × 4.0 mm |
| 0.75 ct | 5.8 mm | 7.0 × 5.0 mm |
| 1.00 ct | 6.4 mm | 7.7 × 5.7 mm |
| 1.50 ct | 7.4 mm | 9.0 × 6.5 mm |
| 2.00 ct | 8.1 mm | 10.0 × 7.0 mm |
| 3.00 ct | 9.3 mm | 11.5 × 8.0 mm |
Measurements vary slightly with proportions. Elongated shapes such as oval, pear and marquise spread their weight over a larger surface and look bigger per carat than a round diamond.
How to balance the 4Cs
Start with the cut, because it drives beauty. Then decide on size and shape, the qualities you notice first on the hand. Colour and clarity should simply be high enough that nothing distracts from the sparkle. With lab-grown diamonds you do not have to choose: we combine an excellent cut with D colour and VVS–VS1 clarity, and every centre diamond comes with an independent IGI certificate that documents all four Cs.
