FIRE & BRILLIANCE: THE ULTIMATE RADIANT VS. PRINCESS CUT GUIDE

Left: The chaotic brilliance of the Radiant. Right: The structured fire of the Princess.

It is the eternal debate for the client who wants maximum sparkle in a square(ish) shape. Do you choose the crisp, modern lines of the Princess Cut? or the edgy, durable brilliance of the Radiant Cut?

At first glance, they might look similar—both are brilliant cuts, both have intense light return, and both are non-round. But structurally, optocially, and practically, they are worlds apart.

In this guide, we break down the battle of the sparkles. We will reveal why active women should almost always choose the Radiant, why the Princess Cut is the "X" factor of fire, and how the elongation trend of 2026 has shifted the market.

Visual Detail: Sparkle Comparison

ORIGINS: THE SQUARE REVOLUTION

Before 1977, if you wanted a square diamond, you had to settle for a Step Cut (Emerald/Asscher) which sparkled less, or a Cushion Cut which was "pillowy" and not a true square.

The Radiant Revolution (1977)

Master cutter Henry Grossbard changed everything. He wanted to combine the elegant, cut-cornered shape of the Emerald Cut with the brilliance of the Round. After years of experimentation, he patented the Radiant Cut. It was the first time significant fire and brilliance were achieved in a square shape. Grossbard famously said he "liberated the square diamond."

The Princess Evolution (1980)

Three years later, Betzalel Ambar and Israel Itzkowitz took it a step further. They created the "Quadrillion" (later known as the Princess Cut). Their goal wasn't just sparkle—it was weight retention. The Princess Cut shape mimics the natural octahedral crystal of a rough diamond. This means a cutter can retain up to 80% of the rough stone (compared to 40-50% for a Round), making it significantly less expensive per carat.

DEEP DIVE: PHYSICS OF SPARKLE

Both cuts are modified brilliants, but they manipulate light in fundamentally different ways. This is the difference between "Fire" and "Ice."

Princess Cut: The "Chevron" Structure

If you look at the bottom (pavilion) of a Princess Cut, you will see distinct "V" shapes running from the center to the corners. These are called Chevrons.

The Effect: When light enters, it hits these long, flat chevron facets and bounces back in structured, orderly flashes. A high-quality Princess Cut displays a distinct "Black Cross" or "X" pattern in the center when viewed face-up. This structure creates intense Fire (spectral rainbow flashes).

Zizov Tip: The more chevrons a Princess has (2, 3, or 4 bands), the more "crushed" the look. We prefer 3-chevron stones for the perfect balance of bold flashes and scintillation.

Radiant Cut: The "Shattered Glass" Effect

The Radiant Cut does not have chevrons. Instead, its pavilion is covered in a complex web of small, irregular facets.

The Effect: Light enters the stone and is scrambled. It bounces off multiple tiny mirrors before exiting. This creates a mesmerizing "Crushed Ice" or "Shattered Glass" look. There is no pattern, no "X," and no order. Just pure, chaotic Scintillation (white sparkles).

Look closely: A well-cut Princess will show a distinct "X" in the center, while a Radiant is uniform glitter.

THE PRINCESS CUT: SHARP PRECISION

The defining feature of the Princess Cut is its sharp, 90-degree corners. It is the only brilliant square shape with pointed corners.

The Pro: Unmatched geometric precision. It looks incredibly modern and clean. It also uses more of the rough crystal, making it less expensive per carat.

The Con: Those corners are fragile. As we discussed in our Princess Cut Guide, they must be protected by V-prongs to prevent chipping.

THE RADIANT CUT: THE DURABILITY KING

The Radiant Cut looks like a rectangle with cut corners (beveled). It is essentially an octagon, though looking at it, your eye registers it as a rectangle.

The Radiant's beveled corners (right) make it significantly more durable than the Princess (left).

The Pro: Durability. Because there are no sharp points to snag or chip, the Radiant Cut is the #1 choice for women with active lifestyles (doctors, athletes, mothers). You can set it with standard claw prongs without fear.

The Con: It can sometimes look "bottom heavy" or deep if not cut well.

SIDE-BY-SIDE: THE 4 FACTORS

THE RATIO GUIDE (RADIANTS)

While Princess cuts are almost always square (1.00 – 1.05), Radiants are chameleons.

Square Radiant (1.00 – 1.05)

Princess Cut Ratios: The Square Law

Unlike Radiants, Princess cuts must be square.

1.00 – 1.05 Ratio: The "Safe Zone." This ensures the facet pattern (the "X") is symmetrical and the light return is balanced.
> 1.05 Ratio: The "Rectangular Princess." These are often cut to save weight from a weirdly shaped rough crystal. The result is usually a loss of brilliance and a "mushy" pattern. Avoid these unless you are getting a massive discount.

DEEP DIVE: THE RADIOACTIVE BOW-TIE

If you are buying an Elongated Radiant, you must know about the Bow-Tie.

What is it? A dark, black shadow across the center of the stone that looks like a man's bow tie.
Why does it happen? In elongated shapes (Oval, Pear, Radiant), light rays that enter the center sometimes leak out the bottom instead of reflecting back to your eye.
Is it bad? Yes if it's black. No if it's just a subtle contrast.

The Zizov Rule: We accept a "shadow" (light grey), but we reject "blackouts." A strong bow-tie kills the sparkle in the most important part of the stone.

BEST SETTINGS FOR SQUARE CUTS

Your choice of cut will dictate your setting style.

1. The Solitaire (Winner: Radiant)

A Radiant cut looks massive in a thin, pavé band solitaire. The cut corners allow for standard claw prongs (eagle claw or petite claw), which look very delicate.
The Princess Issue: A Princess solitaire requires bulky V-prongs at the corners to protect them. This can make the ring look "heavy" or industrial.

2. The Halo (Winner: Princess)

Because the Princess cut has straight edges and sharp corners, a halo fits it perfectly with no gaps. It creates a seamless "wall of sparkle."
The Radiant Issue: Radiants have cut corners. A square halo leaves gaps. An octagonal halo is custom work. It is harder to get a "seamless" look with a Radiant halo.

3. The Three-Stone (Draw)

Princess + Trillions: The sharp lines of triangular side stones (Trillions) match the sharp corners of the Princess perfectly. It looks like a spaceship—futuristic and sleek.
Radiant + Trapezoids: The clear, step-cut lines of Trapezoid side stones contrast beautifully with the chaotic sparkle of the Radiant center. This is the classic "Harry Winston" look.

THE COLOR TRAP

Why do we keep mentioning color? Because physics.

The Radiant Trap: The radiant cut was literally invented to intensify light return. This means it also intensifies body color. A "J" color Radiant will look much more yellow than a "J" color Round.
Advice: If you want a white stone, buy H color or higher. If you want a yellow diamond, ALWAYS buy a Radiant.

The Princess Trick: The structured, high-contrast black/white pattern of the Princess cut helps mask color slightly better in the face-up view. However, the sharp corners can concentrate color.
Advice: You can often get away with an I color Princess if the corners are covered by prongs.

Elongated Radiant (1.15 – 1.25)

This is the "It Girl" shape of 2026. An elongated radiant offers massive finger coverage (looking larger than a Round of the same weight) and creates a lengthening effect on the hand.

The 1.25 ratio Elongated Radiant is currently the most requested shape in our Brussels showroom.

CELEBRITY HEAVYWEIGHTS

Nothing sways the market like a celebrity engagement ring. Here is who is wearing what.

Team Radiant

• Jennifer Lopez: When Ben Affleck proposed (the second time), he chose a rare 8.5-carat Green Radiant diamond. The soft corners and intense color return made it the perfect choice for a fancy colored stone.
• Megan Fox: Her "Toi et Moi" ring features a Radiant cut paired with a Pear shape. The geometric lines of the Radiant balance the soft curves of the pear.
• Khloe Kardashian: Often seen sporting a massive Radiant cut with a halo, proving that this shape can handle "more is more" styling.

Team Princess

• Emily Ratajkowski: Typically a trendsetter, EmRata’s "Toi et Moi" ring features a massive 2-carat Princess cut next to a Pear. She chose the Princess for its sharp, modern, architectural lines.
• Jaime Pressly: Her engagement ring is a classic solitaire Princess cut, letting the sharp corners define the look.

THE ZIZOV BUYING CHECKLIST

Use these numbers to filter out the duds. Note that Princess cuts effectively have "looser" standards because they are cut to save weight.

CASE STUDY: 2.00CT PRINCESS VS 2.00CT RADIANT

We pulled two G/VS1 diamonds from our vault to compare them side-by-side.

Diamond A: 2.01ct Princess Cut
Dimensions: 6.95mm x 6.90mm
Look: Precise, sharp, incredible rainbow flashes. Looks very geometric.

Diamond B: 2.03ct Elongated Radiant
Dimensions: 8.80mm x 6.50mm
Look: Huge. The elongation makes it cover more of the finger length. The sparkle is like a glitter bomb.

The Verdict:
If you want "Big," go with the Elongated Radiant. It faces up 15% larger visually due to the shape.
If you want "Modern/Edgy," go with the Princess. The sharp corners give it an architectural vibe that the Radiant lacks.

THE CUT GRADING PROBLEM: A SCANDAL?

Here is a secret most jewelers won't tell you: GIA does not give a Cut Grade for Princess or Radiant cuts.

If you buy a Round Brilliant, you get a "Cut Grade" (Excellent, Very Good, etc.). But for Fancy Shapes (Princess, Radiant, Oval, etc.), GIA only grades Polish and Symmetry.

Why is this a problem?
You can have a Princess cut with "Excellent" Polish and "Excellent" Symmetry that effectively has a "Poor" cut. It might be too deep (leaking light), too shallow (fisheye), or have a dead center.

The Solution: The ASET Scope.
Since the paper certificate won't tell you if the diamond sparkles, you need to see the light performance data. Advanced jewelers (like Zizov Diamonds) use an ASET Scope (Angular Spectrum Evaluation Tool). This tool color-codes the light return:
Red: Intense light return (What you want).
Green: Reflected light (Good contrast).
Blue: Obscured light (Contrast/Head shadow).
White/Black: Light leakage (Bad).

THE FLUORESCENCE FACTOR

Fluorescence is the tendency of a diamond to glow blue under UV light. In Round Brilliants, Medium-Strong fluorescence lowers the price by 10-15%. In Radiants, it is more complicated.

The "Milky" Risk: Because Radiants have so many facets and heavy "crushed ice" scintillation, Strong Fluorescence can sometimes make the stone look oily or milky in sunlight. It kills the crispness.

The Opportunity: If you find a Radiant with "Medium Blue" fluorescence that is verified crisp and clear (no milkiness), you can save 15% on the price. This is a great "hack" for budget buyers, but only if you can inspect the stone visually.

LAB-GROWN RADIANTS: A WARNING

Radiant cuts are currently the most popular shape for Lab-Grown Diamonds. Because they can be grown quickly and cut to maximize weight, the market is flooded with them.

The "Brown" Tint: Many CVD (Chemical Vapor Deposition) lab-grown radiants have a subtle brown or grey undertone due to the vacuum growth process. Even if graded "G" or "H," they can look muddy compared to a natural diamond.

The "Strain" Lines: Low-quality lab radiants often have "strain lines" (striations) that look like faint vinegar streaks in the stone. These blur the sparkle. If you are buying Lab-Grown, ensure it is "As Grown" (no post-growth treatment) and inspected for striations.

FREQUENTLY ASKED QUESTIONS