Oval cut diamonds are a modern favorite among engagement ring shoppers - and for good reason. Their elongated shape, brilliant sparkle, and finger-flattering silhouette make them one of the most elegant and versatile diamond shapes available.
In this guide, you'll learn:
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What makes the oval diamond cut special
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Why size perception matters with oval stones
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A complete Oval Cut Diamond Size Chart (millimeters to carats and vice versa)
✨ What Is an Oval Cut Diamond?
An oval cut diamond is a modified brilliant-cut, combining the fire and brilliance of a round diamond with a stretched, elongated shape. Originally developed in the 1960s, this cut features 58 facets and is admired for:
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Brilliance similar to round cuts
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A larger face-up size for the same carat weight
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A slimming effect on the finger
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A modern yet timeless appeal
✅ Pro Tip: Oval diamonds hide inclusions well and offer great value per carat, making them an ideal choice for engagement rings.
📏 Why You Need an Oval Diamond Size Chart
Carat weight ≠ size.
Two oval diamonds with the same carat weight can appear quite different depending on depth, length-to-width ratio, and cut quality.
That’s where a size chart helps. It shows:
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The approximate dimensions in millimeters (mm) for each carat weight
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The carat estimate based on visible size (mm)
This is crucial when shopping online or comparing styles.
Oval Cut Diamond Size Chart (MM to Carat & Carat to MM)
| Carat | Length (mm) | Width (mm) | Approx. MM Size (L × W) | Estimated Carat by MM Size |
|---|---|---|---|---|
| 0.25 ct | 5.0 | 3.5 | 5.0 × 3.5 | 0.25 ct |
| 0.33 ct | 5.5 | 3.8 | 5.5 × 3.8 | 0.33 ct |
| 0.50 ct | 6.0 | 4.0 | 6.0 × 4.0 | 0.50 ct |
| 0.75 ct | 7.0 | 5.0 | 7.0 × 5.0 | 0.75 ct |
| 1.00 ct | 7.5 | 5.5 | 7.5 × 5.5 | 1.00 ct |
| 1.25 ct | 8.0 | 5.8 | 8.0 × 5.8 | 1.25 ct |
| 1.50 ct | 9.0 | 6.0 | 9.0 × 6.0 | 1.50 ct |
| 1.75 ct | 9.5 | 6.5 | 9.5 × 6.5 | 1.75 ct |
| 2.00 ct | 10.0 | 7.0 | 10.0 × 7.0 | 2.00 ct |
| 2.50 ct | 11.0 | 7.5 | 11.0 × 7.5 | 2.50 ct |
| 3.00 ct | 12.0 | 8.0 | 12.0 × 8.0 | 3.00 ct |
| 4.00 ct | 13.0 | 9.0 | 13.0 × 9.0 | 4.00 ct |
| 5.00 ct | 14.0 | 10.0 | 14.0 × 10.0 | 5.00 ct |
🔍 Note: These sizes are approximate. Each diamond may vary slightly depending on cut proportions and length-to-width ratios.
Ideal Length-to-Width Ratio for Oval Diamonds
The ideal length-to-width ratio for an oval diamond is typically between 1.35 and 1.50. This gives a balanced, elegant look - not too round, not too skinny.
| Ratio | Look |
|---|---|
| 1.30–1.39 | Fuller, wider oval |
| 1.40–1.50 | Classic balanced shape |
| 1.51–1.60 | Slender, elongated |
Choose based on personal taste and finger shape. Some prefer a long, lean look; others want a fuller center stone.
How to Choose the Right Oval Diamond Size
Here are tips to guide your decision:
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✋ Finger size matters: Smaller fingers may suit 0.50–1.00 ct; larger hands can balance 1.50–3.00+ ct stones
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📷 Optical illusion: Oval diamonds look larger than rounds of the same carat due to their stretched surface
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💍 Setting style: Halo or bezel settings make the diamond appear even larger
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🎯 Budget: You can go slightly lower in carat and still get major visual impact
Final Thoughts: Choosing the Perfect Oval Diamond
Oval diamonds offer unmatched elegance and brilliance in a unique shape that flatters every hand. Using a diamond size chart ensures you get what you expect - no surprises in how your stone looks in person.
Whether you're shopping for an engagement ring, anniversary gift, or simply investing in fine jewelry, knowing your carat-to-mm conversion is key to buying smart.
