The 4Cs
Four measurements decide what a diamond costs. Only one decides how it looks. Understanding the difference is the single most valuable thing a buyer can learn; it is how informed people buy better stones for less.
Cut, the one that makes light
Cut is not the shape; it is the geometry, how precisely the facets are angled to catch light and throw it back. A perfectly cut diamond is a hall of mirrors; a poorly cut one of the same weight and color is a sleepy piece of glass. Cut is the only C visible from across a room, and the only one we refuse to compromise: look for Excellent cut, polish and symmetry on the certificate.
Carat, the one everyone asks about
Carat measures weight, not size. Price moves in steps at the round numbers, while visible size barely changes, a well-cut 0.90 ct is nearly indistinguishable from 1.00 ct on the hand. We map every carat to its real millimetre size in our carat size guide.
Color, graded on paper, invisible in person
The D-to-Z scale grades the absence of warmth. Side by side under laboratory light, a D and a G differ; on a finger, in real light, set in a ring, the difference all but disappears. G–H is the connoisseur’s zone, whiteness the eye confirms, at a price the paper doesn’t punish.
Clarity, buy with your eyes, not the loupe
Clarity grades describe what a grader sees at 10× magnification. Nobody will ever wear a microscope. The concept that matters is eye-clean: no inclusion visible to the naked eye, and it is regularly achieved at VS2 and SI1 grades, far below the prices of VVS perfection. We explain how the trade buys for itself in the eye-clean guide.
How to balance the four
- Never trade away cut. Excellent, always.
- Buy carat just under the steps, 0.90 instead of 1.00, 1.40 instead of 1.50.
- Sit in G–H color, VS2–SI1 clarity, confirmed eye-clean on video or in person.
- Spend the savings on the setting; it’s the part she sees every day.
Every stone in our collection lists all four Cs from its GIA or HRD report, with a 360° video to confirm what the paper promises.