Diamond Ratio Guide
Understanding Diamond Ratios
A diamond's ratio refers to the relationship between its length and width. While carat weight and measurements determine a diamond's size, the ratio determines its overall shape and visual appearance.
For fancy-shaped diamonds such as Oval, Pear, Emerald, Radiant, Cushion, and Marquise cuts, the ratio plays a significant role in how the diamond looks when viewed from above.
Choosing the right ratio is largely a matter of personal preference, as different ratios can create dramatically different appearances even when two diamonds have the same carat weight.
How Diamond Ratios Are Calculated
The ratio is calculated by dividing the diamond's length by its width.
For example:
Length: 10.0 mm
Width: 7.0 mm
Ratio: 10.0 ÷ 7.0 = 1.43
The higher the ratio, the more elongated the diamond appears.
A lower ratio creates a shorter and wider appearance.
Why Diamond Ratios Matter
Diamond ratios influence:
• Overall shape appearance
• Finger coverage
• Visual size perception
• Ring design aesthetics
• Personal style preferences
Two diamonds with identical carat weights may look completely different due to their ratios.
Oval Diamond Ratios
Oval diamonds are among the most ratio-sensitive shapes.
Popular Oval Ratios:
• 1.30 – Soft and wider appearance
• 1.35 – Balanced classic oval
• 1.40 – Most popular proportion
• 1.45 – Elegant elongated look
• 1.50+ – Long and slender appearance
Recommended Range:
1.35 – 1.45
This range typically provides the best balance between elegance and visual width.
Cushion Diamond Ratios
Cushion diamonds can appear square or rectangular depending on their ratio.
Popular Cushion Ratios:
• 1.00 – Perfect square cushion
• 1.05 – Slightly rectangular
• 1.10 – Balanced rectangular cushion
• 1.15+ – Noticeably elongated cushion
Recommended Range:
1.00 – 1.10
Emerald Cut Ratios
Emerald cuts are famous for their elegant rectangular silhouette.
Popular Emerald Ratios:
• 1.25 – Wider appearance
• 1.35 – Classic emerald cut
• 1.40 – Highly popular
• 1.50 – Long sophisticated appearance
Recommended Range:
1.30 – 1.45
Radiant Cut Ratios
Radiant cuts are available in both square and rectangular formats.
Popular Radiant Ratios:
• 1.00 – Square radiant
• 1.10 – Slight rectangle
• 1.20 – Balanced rectangular radiant
• 1.30+ – Elongated radiant
Recommended Range:
1.10 – 1.30
Pear Diamond Ratios
Pear diamonds combine the brilliance of a round diamond with an elegant elongated shape.
Popular Pear Ratios:
• 1.45 – Fuller appearance
• 1.50 – Classic pear shape
• 1.60 – Elegant balance
• 1.70 – Slender appearance
• 1.80+ – Highly elongated
Recommended Range:
1.50 – 1.70
Marquise Diamond Ratios
Marquise diamonds naturally feature elongated proportions.
Popular Marquise Ratios:
• 1.75 – Fuller shape
• 1.90 – Traditional marquise
• 2.00 – Elegant balance
• 2.10 – Long appearance
• 2.20+ – Extremely elongated
Recommended Range:
1.85 – 2.10
Which Ratio Looks Larger?
Generally, elongated diamonds appear larger than wider diamonds of the same carat weight because they cover more surface area visually.
Shapes that often appear larger include:
• Oval
• Marquise
• Pear
• Emerald
• Elongated Radiant
However, selecting a ratio solely for size may compromise overall balance and beauty.
Choosing the Perfect Ratio
There is no universally perfect diamond ratio. The ideal ratio depends on:
• Personal style
• Ring design
• Finger shape
• Desired appearance
• Overall proportions
Some buyers prefer shorter and wider diamonds, while others prefer long, elegant silhouettes.
At Bespoke Carat, we help clients evaluate ratios alongside measurements, proportions, and overall cut quality to ensure every diamond achieves the desired visual effect.
Custom Ratios & Bespoke Diamonds
One of the advantages of custom-cut diamonds is the ability to create specific ratios tailored to your vision.
Whether you're searching for a perfectly balanced Oval, an elongated Radiant, or a unique custom shape, Bespoke Carat can source and create diamonds with precise ratios to match your design requirements.