Cut — the one that matters most
Cut is not the same as shape. It describes how precisely a diamond's facets are proportioned to catch and return light. A well-cut diamond is full of fire and sparkle; a poorly cut one looks dull and lifeless, even with a top colour and clarity grade. If you remember one thing, make it this: prioritise cut above every other C.
Colour
Diamond colour is graded from D (completely colourless) to Z (light yellow). The less colour a diamond has, the rarer and brighter-white it appears. In white-gold or platinum settings, D–F look icy and pure; G–J are near-colourless and offer outstanding value — the slight warmth is invisible to the naked eye once set. Yellow- and rose-gold settings hide warmth beautifully, so you can comfortably choose a lower grade.
Clarity
Clarity measures the tiny natural marks — called inclusions — that form inside almost every diamond. It's graded from Flawless (FL) down to Included (I). The good news: most inclusions are microscopic. A diamond graded VS1–VS2, and many SI1 stones, are "eye-clean" — perfectly flawless to the naked eye — which is where the smart value lives.
Carat
Carat is a measure of weight, not size (one carat = 0.2 grams). Two diamonds of equal carat can look different sizes depending on how they're cut. Prices also jump at the "magic" weights — 1.0ct, 1.5ct, 2.0ct — so choosing a 0.90ct over a 1.00ct, or 1.9ct over 2.0ct, can save meaningfully with no visible difference on the finger.
Spend on cut first, choose an eye-clean clarity (VS–SI) and a near-colourless grade (G–H), then put the rest of your budget into carat. Because every Renaissance diamond is lab-grown, that same budget buys a noticeably larger, higher-grade stone.