The 4Cs of a diamond, explained simply
Carat, colour, clarity and cut – what each one means and where you can save money without seeing a difference.
Every diamond grading report describes a stone with four values, the 4Cs. Together they decide how a diamond looks and what it costs.
Carat – the weight
One carat is 0.2 grams. Price rises faster than weight: a 1.00 ct stone costs clearly more than two 0.50 ct stones. Stones just below a "magic" weight (0.90 ct instead of 1.00 ct) look almost the same size and often cost noticeably less.
Colour – how white the stone is
The scale runs from D (colourless) to Z (light yellow). D–F are colourless, G–J near colourless. Set in yellow or rose gold, G–I usually looks white; in platinum or white gold many buyers choose E–G.
Clarity – inner features
From FL (flawless) via IF, VVS1/VVS2, VS1/VS2, SI1/SI2 down to I1–I3. From VS2 upwards, features are normally invisible to the naked eye ("eye clean"). Many SI1 stones are eye clean too – the report photo helps.
Cut – how well the stone is cut
Cut decides brilliance and sparkle. For round diamonds the labs grade it from Excellent (GIA) or Ideal (IGI) down to Poor. Cut is the C where we would compromise least.
Our tip
Excellent cut, colour G–H, clarity VS2–SI1 and a weight just below a round number give the most beauty for the budget.