Quick answer: Every diamond is graded on four qualities — Cut, Colour, Clarity and Carat. Cut matters most for sparkle and is the one never to compromise. Colour is graded D (colorless) to Z; most people look white and save money at G–H. Clarity runs FL to I; aim for "eye-clean" at VS2 or SI1. Carat is weight, not size. Buy well by knowing where to spend and where to ease off — and by reading the grading report.
What is Cut, and why does it matter most?
Cut is not the shape of the diamond — it's how well the stone was cut: its proportions, symmetry and polish. It is the single biggest driver of a diamond's beauty. A well-cut diamond catches light and throws it back as brightness (the white light it returns), fire (flashes of color) and scintillation (the sparkle as it moves). A poorly cut stone leaks light and looks dull, even when everything else about it is excellent.
GIA grades cut only on round brilliants, from Excellent to Poor, as a combined evaluation of face-up appearance, design and craftsmanship. Fancy shapes have no official cut grade — which is why judging them well, and trusting who cut them, matters even more. If you protect one of the 4Cs above all others, protect Cut. It's what makes a diamond look alive.
What are the parts of a diamond's cut?
A faceted diamond has a few key parts, and their proportions decide how it handles light:
- Table — the large flat facet on top; the window light enters and exits through.
- Crown — the angled top section, between the table and the widest point.
- Girdle — the thin band around the widest point, where the ring's setting grips.
- Pavilion — the cone-shaped bottom that reflects light back up to your eye.
- Culet — the tiny point (or facet) at the very bottom.
Two proportions do most of the work: table percentage (how wide the table is relative to the diamond) and depth percentage (how deep the stone is top to bottom). Get them right and light bounces back to your eye; get them wrong and the stone shows a window (light leaking straight through) or extinction (dark, lifeless areas). This is the "why" behind a great cut grade.
What makes an ideal-cut diamond?
An ideal-cut diamond has proportions tuned so almost all the light that enters is returned to your eye as brightness, fire and scintillation — not leaked out the back. On round brilliants, well-cut stones often show a "hearts and arrows" pattern (a symmetrical arrows pattern face-up, hearts face-down) — a visual shorthand for precise symmetry. It's a nice signal, but the grade that matters is the overall Cut grade on the report.
What is diamond fluorescence — is it good or bad?
Fluorescence is a soft glow — usually blue — that some diamonds give off under ultraviolet light (like sunlight or a club's black light). About a quarter to a third of diamonds have some fluorescence, and on its own it is neither good nor bad.
- In lower colour grades (I–M), faint-to-medium blue fluorescence can actually make a stone face up whiter, because blue offsets yellow — a quiet value opportunity.
- In the very top colours (D–F), strong fluorescence occasionally makes a stone look slightly hazy or "oily" in direct sun — worth checking in person or on video.
The honest takeaway: don't fear faint or medium fluorescence — it's often a way to pay less for a white-looking stone. Just eyeball a strong fluorescence grade before committing.
What are Polish and Symmetry on a diamond report?
Polish and Symmetry are two finishing grades, separate from the overall Cut grade:
- Polish — how smooth the facet surfaces are (no fine polishing lines).
- Symmetry — how precisely the facets line up and match.
Aim for Excellent or Very Good on both. Poor polish or symmetry can slightly dull a diamond's sparkle even when the proportions are good — but you don't need to pay a premium for flawless finishing you can't see.
What is diamond Colour, and what does "colorless" mean?
Diamond colour is graded from D (completely colorless) down to Z (light yellow or brown). Counterintuitively, less color is rarer and more prized.
| Grade range | What it means | In plain terms |
|---|---|---|
| D–F | Colorless | The whitest, and the most expensive |
| G–J | Near-colorless | Faces up white to the eye, especially once set — much friendlier price |
| K–Z | Faint to light colour | Visible warmth; a look some people love |
For most people, a stone in the G–H range looks white on the hand and costs far less than a D. That's one of the smartest places to save. (This D–Z scale applies to white diamonds; fancy colored diamonds — yellow, pink, blue — are graded on a different, opposite scale. See "Colored diamonds.")
How is diamond colour graded?
Colour is graded by comparing a diamond, face-down, against a set of masterstones of known colour, under controlled, neutral lighting. Grading face-down and in fixed lighting removes the sparkle and the room's light from the judgment, so the grader is reading true bodycolor, not reflections. It's why a lab grade is more reliable than eyeballing a stone under a jeweler's warm spotlight.
What is diamond Clarity, and what do VVS, VS and SI mean?
Clarity describes a diamond's tiny internal characteristics (inclusions) and surface marks (blemishes) — think of them as the stone's birthmarks, formed as it grew.
| Grade | Meaning | Visibility |
|---|---|---|
| FL / IF | Flawless / Internally Flawless | Extremely rare |
| VVS1–VVS2 | Very, Very Slightly Included | Invisible without magnification |
| VS1–VS2 | Very Slightly Included | Hard to see even under a loupe |
| SI1–SI2 | Slightly Included | Often invisible to the naked eye — "eye-clean" |
| I1–I3 | Included | Inclusions visible to the eye |
The goal for most buyers is an eye-clean stone — one with no inclusions visible without magnification. You often find that at VS2 or SI1, without paying for perfection you can't see.
What kinds of inclusions do diamonds have?
Not all inclusions are equal — what matters is whether you can see one and whether it affects durability. Common types:
- Crystal — a tiny mineral crystal trapped inside.
- Feather — a small internal fracture; usually harmless, but a large one near the girdle is worth avoiding for durability.
- Cloud — a hazy cluster of microscopic pinpoints; a dense one can dull transparency.
- Needle — a thin, rod-like inclusion.
Position matters as much as size: an inclusion under the table is more visible than one hidden near the girdle where a prong can cover it. A good report's plot shows you exactly where they sit.
How do I read a diamond grading report?
A grading report (GIA or IGI) is the diamond's independent ID card. Read it in this order:
- The 4Cs — Cut (round only), Colour, Clarity, Carat weight.
- Proportions diagram — the profile drawing with table % and depth %; this is where the cut quality lives.
- Polish and Symmetry — aim Excellent/Very Good.
- Fluorescence — None to Strong (see above).
- The clarity plot — a map of where the inclusions are.
- The report number — laser-inscribed on the girdle, so you can verify the exact stone matches the paper.
The report is proof, not a promise. Every diamond DelaFuente sells comes with one, and we'll walk you through it line by line.
And here's how to verify it yourself: both labs run free online databases — GIA's Report Check and IGI's report verification — where you type the report number and see the full grading record. If the number on the girdle matches the paper and the paper matches the database, you know exactly what you own. Thirty seconds, zero trust required. (A "certificate" that can't be verified online is a red flag, full stop.)
What is Carat — is it size or weight?
Carat is a measure of weight, not size — one carat equals 0.2 grams. Two diamonds of the same carat weight can look like different sizes, because cut and shape determine how much of that weight sits on top, visible from above, versus hidden in depth.
Carat is also where price climbs fastest — and it doesn't climb smoothly. Price jumps at "magic" weights like 0.50, 1.00 and 2.00 ct, because demand clusters at round numbers. Choosing a stone just under one — say 0.90 ct instead of 1.00 ct — can look identical on the hand for meaningfully less, because you're paying below the premium threshold.
How do you balance the 4Cs with a budget?
You rarely need to maximize all four. The move is knowing where to spend and where to ease off:
- Never compromise on Cut. It's what makes the diamond sparkle.
- Ease off Colour to G–H — it still faces up white, especially in yellow or rose gold.
- Ease off Clarity to a VS2 / SI1 that's eye-clean — no one sees inclusions they can't see.
- Spend the savings on Carat or Cut, whichever matters more to you.
Tell us your budget and your priority — bigger, whiter, or brighter — and we'll build the stone around it.
Certification: what's the difference between GIA and IGI?
A diamond certificate (or grading report) is an independent laboratory's unbiased assessment of a stone's 4Cs. It's the difference between our word and a third party's — proof, not a promise.
- GIA (Gemological Institute of America) is the long-standing benchmark, especially for mined diamonds.
- IGI (International Gemological Institute) is the dominant, highly consistent lab for grading lab-grown diamonds.
One recent change worth knowing: since October 2025, GIA no longer issues full 4Cs grades for lab-grown diamonds — it sorts them into a simplified "Premium" or "Standard" quality assessment instead, reserving its granular D–Z and clarity scales for mined stones. In practice that makes the division clean: GIA for mined, IGI for lab-grown with full 4Cs detail.
Both are respected, independent, and non-negotiable for a serious purchase. Every diamond DelaFuente sells is certified, and the report number is laser-inscribed on the stone, so what you receive is verifiably what you paid for.
What are the diamond shapes?
Shape is the outline of the stone — a matter of taste, not quality. The most loved:
- Round brilliant — the most brilliant and timeless; maximum sparkle.
- Oval — elongated and elegant; looks larger per carat.
- Emerald — a "step cut" with long, clean lines and a quiet, sophisticated flash (the "hall of mirrors").
- Pear — a teardrop; slimming on the finger.
- Radiant — brilliant sparkle in a soft rectangle.
- Cushion — a rounded square with vintage romance.
- Marquise — long and pointed; dramatic, maximizes apparent size.
- Princess — a sharp, modern square.
- Asscher — a stepped, geometric square with Art Deco character.
Which diamond shape looks biggest for the money?
Elongated shapes win the size-per-carat game: oval, marquise and pear spread their weight across the finger, so they face up larger than a round of the same carat — and fancy shapes also cost meaningfully less per carat than rounds (round brilliants carry a premium for demand and for the rough they waste in cutting). If maximum sparkle is the goal, round is unbeatable; if maximum presence per dollar is the goal, an elongated fancy shape is the smart play. On smaller hands, those same elongated shapes also visually lengthen the finger.
What is length-to-width ratio and the "bowtie effect"?
For any elongated shape, the length-to-width ratio defines its silhouette — a longer, narrower oval versus a rounder one, for example. It's personal taste, but worth choosing deliberately: a favorite oval ratio sits around 1.35–1.50.
Elongated fancy shapes (oval, pear, marquise) can also show a bowtie — a dark, bowtie-shaped shadow across the center, caused by light passing through instead of reflecting back. A faint bowtie is normal and present in almost every stone; a heavy, dark one is a cutting flaw to avoid. We screen for it so the stone you receive stays bright edge to edge.
