The heart shape diamond is the ultimate symbol of romance - a blend of the brilliance of a round cut with the unique silhouette of a heart. Whether you’re selecting one for an engagement ring, pendant, or special gift, understanding how millimeter dimensions relate to carat weight is key.
Unlike round diamonds, where dimensions are relatively standard, heart shapes can vary slightly in appearance based on length-to-width ratio and cut depth. That means two heart-shaped diamonds with the same carat weight might look different in size.
📐 Why MM-to-Carat Knowledge Matters for Heart Shape Diamonds
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Carat weight tells you the mass of the stone.
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Millimeter size tells you how large it will appear when viewed from the top.
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Choosing the right dimensions ensures your diamond looks perfect for its setting and finger size.
📊 Heart Shape Diamond Size Conversion Chart
| MM (Length × Width) | Approx. Carat Weight | Carat Weight | Approx. MM Size |
|---|---|---|---|
| 5.0 × 5.0 mm | 0.50 ct | 0.50 ct | 5.0 mm |
| 5.5 × 5.5 mm | 0.75 ct | 0.75 ct | 5.5 mm |
| 6.0 × 6.0 mm | 1.00 ct | 1.00 ct | 6.0 mm |
| 6.5 × 6.5 mm | 1.25 ct | 1.25 ct | 6.5 mm |
| 7.0 × 7.0 mm | 1.50 ct | 1.50 ct | 7.0 mm |
| 7.5 × 7.5 mm | 2.00 ct | 2.00 ct | 7.5 mm |
| 8.0 × 8.0 mm | 2.50 ct | 2.50 ct | 8.0 mm |
| 8.5 × 8.5 mm | 3.00 ct | 3.00 ct | 8.5 mm |
| 9.0 × 9.0 mm | 3.50 ct | 3.50 ct | 9.0 mm |
| 9.5 × 9.5 mm | 4.00 ct | 4.00 ct | 9.5 mm |
Note: Sizes are averages; actual appearance may vary depending on depth, table percentage, and cut style.
💡 Tips for Choosing the Right Heart Shape Size
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Balance between sparkle and shape – Too deep a cut can make the heart look smaller; too shallow can affect brilliance.
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Ideal length-to-width ratio – A ratio between 0.90–1.00 gives a pleasing, balanced heart outline.
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Consider setting style – A halo can add perceived size without extra carat cost.
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Finger size factor – Smaller fingers can make a smaller carat weight appear larger.
When buying a heart shape diamond, knowing the mm-to-carat relationship ensures you get the most beauty for your budget. Understanding proportions and dimensions helps you choose a diamond that fits your style, setting, and personal preferences - making your love story shine as bright as the stone itself.
