The 4Cs of Lab-Grown Diamonds Explained

1. Cut — The Most Important C

Cut refers not to a diamond’s shape but to how well its facets interact with light. A perfectly cut diamond reflects light back through its crown in a dazzling display of brilliance, fire, and scintillation. A poorly cut diamond — too shallow or too deep — lets light escape through the sides or bottom, producing a dull, “fisheye” appearance.

The GIA grades cut on a scale of Excellent / Very Good / Good / Fair / Poor. We only supply Excellent or Very Good cut grades. For round brilliants, look for an “Excellent” or “Ideal” cut — this has the largest impact on how beautiful the diamond looks, more than any other factor.

2. Colour — Colourless Is King

The GIA colour scale runs from D (perfectly colourless) to Z (light yellow). D, E, and F are colourless — the highest grades. G, H, I, and J are near-colourless; the warmth is nearly impossible to detect without comparison stones. K–Z show visible colour.

Practical guide: if you are setting the diamond in white gold or platinum, choose D–F to avoid contrast with the white metal. In yellow or rose gold, G–H looks beautiful — the warm metal masks any trace of colour in the diamond, and you save significantly compared to D–F grades.

3. Clarity — Eye-Clean Is the Sweet Spot

Clarity grades describe the number and visibility of internal inclusions (and external blemishes) on the GIA scale: FL, IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3. Flawless (FL) diamonds are exceptionally rare; the sweet spot for value is VS1–VS2, which are eye-clean (inclusions invisible to the naked eye) but significantly cheaper than VVS or Flawless.

Avoid SI2 and below in emerald cuts — the step facets act like mirrors, making inclusions more visible. For round brilliants, SI1 can be eye-clean; always request a photograph or loupe image of the actual stone.

4. Carat — Weight, Not Size

Carat is a measure of weight (1ct = 0.2g), not physical diameter. Two diamonds of the same carat weight can look different sizes depending on their cut proportions and shape. A 1.0ct round brilliant is approximately 6.5mm in diameter. Going from 0.9ct to 1.0ct adds almost nothing visible — but can significantly increase price at the “magic numbers” of 0.5, 0.75, 1.0, 1.5, and 2.0ct. Consider a 0.9ct or 1.4ct for better value.

Recommended 4C Combinations by Budget

Budget	Carat	Colour	Clarity	Cut
€800–1,200	1.0ct	G–H	VS2	Excellent
€1,200–1,800	1.5ct	F–G	VS1–VS2	Excellent
€1,800–2,500	2.0ct	E–F	VS1	Excellent
€2,500+	2.5–3.0ct	D–E	VVS2–VS1	Excellent