Gemological benchmark
The 4Cs: cut, colour, clarity & carat.
Established by the Gemological Institute of America in the 1940s, the 4Cs are the universal standard for assessing diamond quality and value. Here is a cutter’s view of what truly matters when selecting a certified stone.
01Highest visual impact
Cut — the architecture of light
Of all four characteristics, cut has the greatest influence on a diamond’s beauty. It is not the shape, but the precision with which facets are angled and aligned to manipulate light.
Brilliance
Total internal reflection of white light returned through the crown to the eye.
Fire
Dispersion — the prism-like separation of white light into spectral flashes.
Scintillation
Flashes of light and shadow created as the stone or the observer moves.
02D to J
Colour — the absence of tint
In white diamonds, colour grading measures the absence of colour. A chemically pure, structurally perfect diamond has no hue and transmits light with absolute clarity.
03FL to SI2
Clarity — microscopic purity
Diamonds form under enormous geological forces. As crystals grow, microscopic internal features (inclusions) and surface irregularities (blemishes) develop. Clarity measures their size, number, position and nature.
FL / IF
Flawless
VVS1 / VVS2
Very, very slightly included
VS1 / VS2
Very slightly included
SI1 / SI2
Slightly included
04Mass, not size
Carat — the measure of weight
One metric carat equals exactly 200 milligrams (0.20 grams). A common misconception is that carat denotes visual footprint. A poorly cut 1.50 carat stone with excessive depth can appear smaller face-up than a well-proportioned 1.30 carat stone. Always read millimetre measurements alongside carat weight.
Put the 4Cs into practice.
Browse verified inventory filtered by exact colour, clarity and cut parameters.