Triple Excellent Cut: What It Means and Why It Matters

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Triple Excellent means a diamond has been graded Excellent in all three of cut, polish and symmetry by the laboratory that certified it. When jewellers say "cut" they are usually collapsing three separate grades into one word — and the three only deliver together. It is the single biggest driver of how a diamond actually looks on a hand.

Key takeaways

• Cut grade is the proportions that make a diamond return light — it drives brilliance.
• Polish is facet surface smoothness; symmetry is facet alignment.
• Triple Excellent (or 3EX) means all three are Excellent — not just the headline cut grade.
• A stone can be sold as "Excellent cut" while its polish or symmetry sits a grade lower.
• Cut affects how a diamond looks more than colour, clarity or carat.
• It is Montare's floor on every stone — not a tier you upgrade into.

What does Triple Excellent mean?

A grading report does not carry one cut verdict. It carries three, printed as separate lines: cut, polish and symmetry. Each is graded on its own scale running from Excellent down through Very Good, Good, Fair and Poor. When all three read Excellent, the trade calls the stone Triple Excellent, or 3EX.

The distinction matters because the three grades answer different questions. Cut asks whether the stone was designed to return light. Polish asks whether the facets were finished cleanly. Symmetry asks whether they were placed accurately. A diamond can score well on one and poorly on another, and the eye notices the weakest of the three rather than averaging them.

What is the cut grade?

Cut grade is the proportional integrity of the stone — chiefly the angles and relative sizes of the table, crown and pavilion. It has nothing to do with shape. A round, an oval and an emerald cut are all shapes; each can be cut well or badly.

The reason proportions matter so much is a matter of physics rather than taste. Diamond has an unusually high refractive index of about 2.42, which gives it a critical angle of roughly 24.4 degrees. Light striking an internal facet at a shallower angle than that passes straight out of the stone instead of reflecting back. Cut a pavilion too shallow and light escapes through the bottom, leaving a glassy, washed-out patch cutters call a window. Cut it too steep and light is reflected, but off toward the sides rather than up toward your eye. Between those failures sits a narrow band — for a round brilliant, optical modelling puts the ideal pavilion main angle at roughly 40.75 to 41 degrees — where light entering the top comes back out of the top. That returned light is what you perceive as brilliance.

This is why a well-cut diamond outshines a poorly cut one of greater size, higher colour or better clarity. Those attributes describe the material. Cut decides what the material does with light.

What is the polish grade?

Polish grades how smooth the surface of each facet is after the stone leaves the wheel. Cutting a diamond means abrading it against diamond, and that process can leave microscopic drag lines, pits, burn marks or a faint roughness on the facet face. Under magnification these read as fine scratches; in the hand they scatter light at the surface before it ever gets inside the stone, taking a little crispness off every reflection.

An Excellent polish grade means no polish features are visible to a trained grader under 10x magnification. It is the least glamorous of the three grades and the easiest to overlook, but it governs whether the sparkle looks sharp or slightly soft.

What is the symmetry grade?

Symmetry grades how precisely the facets are shaped, sized and aligned with one another — whether the table is centred, whether the girdle runs true, whether opposing facets mirror each other, whether the culet sits on the axis. Poor symmetry distorts the reflection pattern: the tidy geometric arrangement of light and dark that a well-made diamond shows becomes lopsided or smeared.

Symmetry also interacts with cut. Facets that are individually well-angled but collectively misaligned will not deliver the light return their proportions promise. This is precisely why the three grades cannot be traded off against each other. We go deeper on both finishing grades in diamond symmetry and polish grades explained.

Cut, polish and symmetry at a glance

Grade	What it measures	What goes wrong without it	What you see
Cut	Proportions and angles	Light leaks out the sides or bottom	Brilliance and light return
Polish	Facet surface smoothness	Surface scatter softens reflections	Crisp, clean sparkle
Symmetry	Facet shape, size and alignment	The reflection pattern distorts	Even, undistorted flashes

Why "Excellent cut" on its own can mislead

Here is the gap worth knowing about. A diamond graded Excellent in cut but Very Good in symmetry is still, quite legitimately, described in a listing as an "Excellent cut diamond". Nothing false has been said. But it is not Triple Excellent, and the difference is visible in exactly the way the symmetry grade predicts.

Because the headline cut grade is the one that gets quoted, the two finishing grades are where quality quietly slips. They are also cheaper to compromise on: symmetry and polish cost cutting time and yield, and a stone that is a grade down on both still passes as "Excellent cut" in the shorthand everyone uses. Reading all three lines on the report is the only defence, and it takes about five seconds — our guide to reading a diamond certificate shows where they sit. If you are weighing one grade step, we compare them directly in Triple Excellent vs Very Good cut.

Do fancy shapes get a Triple Excellent grade?

This is a genuine and widely misunderstood difference between laboratories. GIA assigns an overall cut grade only to round brilliant diamonds; for ovals, cushions, emeralds and other fancy shapes its reports state polish and symmetry but no overall cut grade. IGI has issued cut grades for fancy shapes since September 2022, assessing proportions and light return alongside the finishing grades.

The consequence is practical. On a fancy shape from a laboratory that does not cut-grade it, "Triple Excellent" cannot mean what it means on a round — because one of the three grades was never issued. If a fancy-shape stone is being sold to you as 3EX, it is worth confirming which laboratory graded it and that all three lines are actually printed.

What Triple Excellent still does not tell you

An Excellent cut grade covers a broader range of proportions than most buyers assume. Two stones can both earn it while differing measurably in table percentage and depth percentage, and those two numbers determine how a stone spreads, how deep it carries hidden weight, and how it handles light at the margins.

This is why Montare holds a second, tighter condition alongside the grade: every stone must also sit inside the ideal table and depth range for its own shape, which is not one universal number. A round brilliant's ideal window is 54–57% table and 59–62.5% depth; an emerald cut's is 62–66% and 61–67%. The full per-shape table is in ideal cut, table and depth explained, with shape-by-shape detail in our guides to table percentage and depth percentage.

Triple Excellent and the 2025 lab-grown grading change

On 1 October 2025, GIA stopped issuing full 4C grades on lab-grown diamonds, replacing them with a two-tier Premium or Standard classification. Cut, polish and symmetry are part of what that classification folds up: under it, Premium corresponds to Excellent polish and symmetry, while Standard accepts Very Good. IGI continues to grade lab-grown diamonds on the full framework, printing cut, polish and symmetry as separate lines exactly as before.

For a brand whose floor is stated as Triple Excellent, that difference is decisive. A tier label that accepts Very Good cannot verify three Excellents, so Montare specifies IGI certification. The change is set out in full in GIA's 2025 lab-grown grading change.

Montare's position

Every diamond we set is Triple Excellent and cut to ideal table and depth for its shape — not as a tier you can pay to reach, but as the floor beneath everything we sell. Cut is the one variable where a premium buys something you can actually see, so it is the one place we refuse to leave a decision open.

Alongside it: lab-grown, D–E colour, VVS1–VVS2 clarity, three carats minimum, IGI certified. The full standard is set out on our standards page. Build a ring to it in the ring builder, or book a consultation.

Frequently asked questions

What does Triple Excellent mean?

It means a diamond was graded Excellent in all three of cut, polish and symmetry — the three separate grades a laboratory prints on its report. It is the strictest combination, and the one that most determines how the diamond looks.

Can a diamond be Excellent cut but not Triple Excellent?

Yes, and this is the most common gap. A stone graded Excellent in cut but Very Good in polish or symmetry can still be described accurately as an Excellent cut diamond, while falling short of Triple Excellent. Checking all three lines on the report is the only way to know.

What is the difference between polish and symmetry?

Polish grades how smooth each facet surface is — whether cutting left microscopic drag lines or pits. Symmetry grades whether the facets are correctly shaped, sized and aligned with one another. Polish affects crispness; symmetry affects whether the reflection pattern is even.

Is Triple Excellent worth paying for?

Yes. Cut is the only factor that determines how much light a diamond returns, and the three grades only deliver together. It is the one premium in diamond buying that changes what you actually see rather than only what the paperwork says.

Does cut matter more than colour and clarity?

For how a diamond looks, yes. A Triple Excellent stone will outshine a higher-colour or higher-clarity stone that is poorly cut, because colour and clarity describe the material while cut decides what the material does with light.

Is Triple Excellent the same as an ideal cut?

They overlap but are not identical. "Ideal" describes proportions — table and depth percentages sitting in the optimal range — while Triple Excellent describes three grades on a report. An Excellent cut grade covers a wider band of proportions than "ideal" does, so Montare requires both.

Do fancy shapes get a Triple Excellent grade?

It depends on the laboratory. GIA assigns an overall cut grade only to round brilliants, so its fancy-shape reports carry polish and symmetry but no cut grade. IGI has cut-graded fancy shapes since September 2022, so all three grades appear on its reports.

Does Triple Excellent guarantee ideal table and depth?

No. An Excellent cut grade spans a broader range of proportions than the ideal window, so two Triple Excellent stones can differ measurably in table and depth. That is why Montare applies a second condition — ideal proportions for the specific shape — on top of the grade.

See the difference cut makes. Build a ring in the ring builder or book a consultation.