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.