Size guides › Radiant
Radiant diamonds
Radiant diamond size chart
An emerald cut's outline with a brilliant's sparkle. A radiant has the trimmed corners of an emerald cut but is faceted like a brilliant, so it's lively and hides small inclusions well. It comes square or rectangular.
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Every radiant size, drawn to scale
From 0.25 to 3 carats, on a millimeter grid. Tap a size to jump to it.
| Carat | Size (mm) | Looks like a round of | Covers of a size 6 finger |
|---|---|---|---|
| 0.25 ct | 4.03 × 3.36 mm | 0.25 ct | 19% |
| 0.5 ct | 5.08 × 4.23 mm | 0.51 ct | 24% |
| 0.75 ct | 5.81 × 4.84 mm | 0.76 ct | 27% |
| 1 ct | 6.39 × 5.33 mm | 1.01 ct | 30% |
| 1.25 ct | 6.89 × 5.74 mm | 1.27 ct | 32% |
| 1.5 ct | 7.32 × 6.10 mm | 1.52 ct | 35% |
| 2 ct | 8.06 × 6.71 mm | 2.03 ct | 38% |
| 2.5 ct | 8.68 × 7.23 mm | 2.53 ct | 41% |
| 3 ct | 9.22 × 7.69 mm | 3.04 ct | 44% |
Typical proportions. Real stones vary by a few tenths of a millimeter — the certificate gives the exact size.
What to know about radiant diamonds
Sparkle that forgives
Brilliant-style facets scatter light in a way that masks small inclusions better than a step cut does.
Square or rectangle
A ratio near 1.00 to 1.05 is square; around 1.20 to 1.35 is the classic rectangle.
Tough corners
Trimmed corners make it more durable than a princess, which has sharp ones.
Length-to-width ratio
Two radiants of the same weight can look quite different. These three all weigh 1 ct; only the ratio changes — from 5.7 mm long at 1.00 : 1 to 6.9 mm at 1.35 : 1. It's a matter of taste, not quality.
Radiant vs round
The dashed line is a 1 ct round. A 1 ct radiant covers about 1% more area from above.
Size by size
Every radiant weight, answered
0.25 carat radiant
How big is a 0.25 carat radiant diamond?
About 4.0 × 3.4 mm, and it looks about as big as a 0.25 ct round. It's about a fifth the width of a US dime (17.91 mm).
Small and delicate
A quarter carat reads as a bright point of sparkle rather than a statement. It's a lovely size for minimalist and stacking rings and for anyone who wants something that sits close and never catches, and it leaves room in the budget for a better cut or color. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Want it to look bigger?
A halo of small diamonds around it takes the face-up width from 3.36 mm to about 4.6 mm — 38% wider — for much less than a bigger center stone would cost.
The same size in other shapes
To cover the same area from above you'd need about 0.25 ct in a round, 0.23 ct in an oval and 0.30 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 4×3.4 mm.
Shop a 0.25 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 0.23–0.27 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
0.5 carat radiant
How big is a 0.5 carat radiant diamond?
About 5.1 × 4.2 mm, and it looks about as big as a 0.51 ct round. It's about a quarter the width of a US dime (17.91 mm).
Petite and practical
Half a carat is a classic petite size: noticeable without being showy, comfortable for everyday wear, and easy to set low so it doesn't snag on gloves or knitwear. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Consider 0.45 ct
Prices tend to step up at round weights like 0.5 ct. A 0.45 ct radiant measures about 4.90 × 4.08 mm — only 0.15 mm narrower, with 7% less area on top. That's very hard to see on a hand.
Want it to look bigger?
A halo of small diamonds around it takes the face-up width from 4.23 mm to about 5.8 mm — 38% wider — for much less than a bigger center stone would cost.
The same size in other shapes
To cover the same area from above you'd need about 0.51 ct in a round, 0.45 ct in an oval and 0.60 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 5.1×4.2 mm.
Shop a 0.5 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 0.46–0.53 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
0.75 carat radiant
How big is a 0.75 carat radiant diamond?
About 5.8 × 4.8 mm, and it looks about as big as a 0.76 ct round. Laid on a US dime (17.91 mm), it would cover about a third of the coin's width lengthwise and a quarter of it across.
Just under the milestone
Three-quarters of a carat gives a good share of the look of a one-carat stone, and on a slim finger the difference can be hard to see. It's a sensible size if the budget is better spent on cut quality or the setting. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Want it to look bigger?
A halo of small diamonds around it takes the face-up width from 4.84 mm to about 6.7 mm — 38% wider — for much less than a bigger center stone would cost.
The same size in other shapes
To cover the same area from above you'd need about 0.76 ct in a round, 0.68 ct in an oval and 0.90 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 5.8×4.8 mm.
Shop a 0.75 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 0.70–0.80 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
1 carat radiant
How big is a 1 carat radiant diamond?
About 6.4 × 5.3 mm, and it looks about as big as a 1.01 ct round. It's about a third the width of a US dime (17.91 mm).
The milestone size
One carat is the size many people picture when they think of an engagement ring. It's clearly a center stone without being heavy, and it suits almost every setting style. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Consider 0.9 ct
Prices tend to step up at round weights like 1 ct. A 0.9 ct radiant measures about 6.17 × 5.14 mm — only 0.18 mm narrower, with 7% less area on top. That's very hard to see on a hand.
The same size in other shapes
To cover the same area from above you'd need about 1.01 ct in a round, 0.90 ct in an oval and 1.20 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 6.4×5.3 mm.
Shop a 1 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 0.93–1.07 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
1.25 carat radiant
How big is a 1.25 carat radiant diamond?
About 6.9 × 5.7 mm, and it looks about as big as a 1.27 ct round. Laid on a US dime (17.91 mm), it would cover about two-fifths of the coin's width lengthwise and a third of it across.
A step past one carat
A quarter carat over the milestone. It reads as noticeably substantial on most hands while still sitting comfortably in standard settings, and it avoids the round-number weights where prices tend to jump. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
The same size in other shapes
To cover the same area from above you'd need about 1.27 ct in a round, 1.13 ct in an oval and 1.50 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 6.9×5.7 mm.
Shop a 1.25 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 1.16–1.34 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
1.5 carat radiant
How big is a 1.5 carat radiant diamond?
About 7.3 × 6.1 mm, and it looks about as big as a 1.52 ct round. Laid on a US dime (17.91 mm), it would cover about two-fifths of the coin's width lengthwise and a third of it across.
A clear statement
At a carat and a half, the stone is the first thing people notice about the ring. It's still easy to wear every day, but cut quality starts to show more, because there's more stone to see. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Consider 1.4 ct
Prices tend to step up at round weights like 1.5 ct. A 1.4 ct radiant measures about 7.15 × 5.96 mm — only 0.14 mm narrower, with 4% less area on top. That's very hard to see on a hand.
The same size in other shapes
To cover the same area from above you'd need about 1.52 ct in a round, 1.35 ct in an oval and 1.80 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 7.3×6.1 mm.
Shop a 1.5 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 1.39–1.60 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
2 carat radiant
How big is a 2 carat radiant diamond?
About 8.1 × 6.7 mm, and it looks about as big as a 2.03 ct round. It's about two-fifths the width of a US dime (17.91 mm).
A large stone
Two carats is big on most hands and is seen from across a room. At this size clarity and color are easier to judge by eye, and a secure head matters more, so ask how it's set. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Consider 1.9 ct
Prices tend to step up at round weights like 2 ct. A 1.9 ct radiant measures about 7.92 × 6.60 mm — only 0.11 mm narrower, with 3% less area on top. That's very hard to see on a hand.
The same size in other shapes
To cover the same area from above you'd need about 2.03 ct in a round, 1.80 ct in an oval and 2.40 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 8.1×6.7 mm.
Shop a 2 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 1.86–2.14 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
2.5 carat radiant
How big is a 2.5 carat radiant diamond?
About 8.7 × 7.2 mm, and it looks about as big as a 2.53 ct round. Laid on a US dime (17.91 mm), it would cover about half of the coin's width lengthwise and two-fifths of it across.
Very large
Two and a half carats is a very large stone for everyday wear. Setting height starts to matter: a lower head snags less, and a sturdy one protects a stone this valuable. Many owners have it appraised for insurance. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
The same size in other shapes
To cover the same area from above you'd need about 2.53 ct in a round, 2.26 ct in an oval and 3.00 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 8.7×7.2 mm.
Shop a 2.5 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 2.32–2.68 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
3 carat radiant
How big is a 3 carat radiant diamond?
About 9.2 × 7.7 mm, and it looks about as big as a 3.04 ct round. Laid on a US dime (17.91 mm), it would cover about half of the coin's width lengthwise and two-fifths of it across.
Dramatic
Three carats is a show-stopping size. It dominates all but the broadest fingers, so seeing it on your own hand before buying matters more here than at any other size. Look for a head made for a stone this size, and insure it. As a radiant, it covers about the same area from above as a round of the same weight, so it reads true to its carat.
Consider 2.9 ct
Prices tend to step up at round weights like 3 ct. A 2.9 ct radiant measures about 9.12 × 7.60 mm — only 0.09 mm narrower, with 2% less area on top. That's very hard to see on a hand.
The same size in other shapes
To cover the same area from above you'd need about 3.04 ct in a round, 2.71 ct in an oval and 3.60 ct in a cushion.
Settings
- Made to orderSolitaire, halo, three stone, bezel, cathedral and east–west — the ready-made heads we could find are for round and oval stones, so ask for one made at 9.2×7.7 mm.
Shop a 3 ct radiant: Blue Nile · Blue Nile, lab-grown · With Clarity · Rare Carat
Blue Nile opens already narrowed to 2.79–3.21 ct at a length-to-width ratio of 1.15 to 1.25 — the range of weights a stone this size can be — so the first page of results is this size rather than every radiant they carry. It also asks for a well-cut radiant's depth (63–73%) and table (58–68%).
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See a radiant on your own hand
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Questions
How big is a 0.25 carat radiant diamond?
About 4.03 × 3.36 mm, and it looks about as big as a 0.25 carat round.
How big is a 0.5 carat radiant diamond?
About 5.08 × 4.23 mm, and it looks about as big as a 0.51 carat round.
How big is a 0.75 carat radiant diamond?
About 5.81 × 4.84 mm, and it looks about as big as a 0.76 carat round.
How big is a 1 carat radiant diamond?
About 6.39 × 5.33 mm, and it looks about as big as a 1.01 carat round.
How big is a 1.25 carat radiant diamond?
About 6.89 × 5.74 mm, and it looks about as big as a 1.27 carat round.
How big is a 1.5 carat radiant diamond?
About 7.32 × 6.10 mm, and it looks about as big as a 1.52 carat round.
How big is a 2 carat radiant diamond?
About 8.06 × 6.71 mm, and it looks about as big as a 2.03 carat round.
How big is a 2.5 carat radiant diamond?
About 8.68 × 7.23 mm, and it looks about as big as a 2.53 carat round.
How big is a 3 carat radiant diamond?
About 9.22 × 7.69 mm, and it looks about as big as a 3.04 carat round.
Do radiant diamonds look bigger than round ones?
Yes. At the same weight a radiant covers about 1% more area from above than a round.
What is the best length-to-width ratio for a radiant?
There's no best — it's taste.
What size setting does a radiant diamond need?
Any common style can be made to fit it: ask for a head the size of the stone — about 6.4×5.3 mm for a 1 ct. Ready-made heads are mostly listed for round stones, so for a radiant choose a setting made to order.