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The nine famous engagement rings below carry center diamonds reported or estimated at about 2.5 to 18 carats or more. In millimeters that runs from about 7.5 × 7.5 mm for a 2.5 carat cushion to about 18.3 × 13.1 mm for an 18 carat emerald cut, against 6.5 mm for a classic 1 carat round.
Numbers like these are hard to picture, so every ring below has a link that opens Find Me Diamond at that shape and carat weight, drawn at actual size on a hand at your own ring size.
Celebrity diamonds are almost never weighed in public. The carat weights here are as reported in the press or estimated by jewelers from photographs, and we name where each figure comes from. Where reports disagree, we give the range.
The millimeter sizes come from the same size model that powers Find Me Diamond, for a well proportioned stone at the classic length to width ratio of each shape. A real stone cut longer, shallower or deeper will measure differently, so treat every size as an estimate. Some of these diamonds are antique style cuts that our model does not include; for those we use the closest modern shape and say so.
Ronora has no connection with any of the people or jewelers mentioned here, and none of them has endorsed Ronora. We describe these rings only to help you picture diamond sizes, and we do not show photographs of them.
| Ring | Reported or estimated weight | Shape used for sizing | Estimated size |
|---|---|---|---|
| Taylor Swift (2025) | Estimated 7 to 10 ct | Elongated cushion (closest to its old mine cut) | 12.5 × 9.6 mm at 8 ct |
| Zendaya (2025) | Reported about 5 ct | Elongated cushion, set east-west | 10.7 × 8.2 mm at 5 ct |
| Selena Gomez (2024) | Estimated 3 to 9 ct | Marquise | 18.2 × 9.1 mm at 6 ct |
| Hailey Bieber (2018) | Reported 6 to 10 ct | Oval | 15.4 × 11.4 mm at 8 ct |
| Meghan, Duchess of Sussex (2017) | Estimated 2.5 to 3 ct (center) | Cushion | 7.9 × 7.9 mm at 3 ct |
| Kim Kardashian (2013) | Reported 15 ct | Cushion | 13.6 × 13.6 mm at 15 ct |
| Blake Lively (2012) | Reported about 12 ct (some reports 7 to 10) | Oval (pink) | 17.6 × 13.0 mm at 12 ct |
| Beyoncé (2007) | Estimated 18 to 24 ct | Emerald | 18.3 × 13.1 mm at 18 ct |
| Grace Kelly (1956) | Reported 10.47 to 10.5 ct | Emerald | 15.3 × 10.9 mm at 10.47 ct |
Travis Kelce proposed with a ring from Artifex Fine Jewelry, and the couple announced their engagement in August 2025. The center stone is widely described as an elongated old mine cut diamond, an antique style cushion shape, set in yellow gold. Jewelers who spoke to TODAY estimated it at about 7 to 10 carats, with several settling near 8. Fortune reported an estimate of about 8 carats, Sotheby's describes it as an estimated 7 carats or more, and The Diamond Collective lists it at about 10.
Our model has no old mine cut, so we size it as an elongated cushion, the closest modern outline. At the often estimated 8 carats that is about 12.5 × 9.6 mm. Across the reported range it runs from about 11.9 × 9.2 mm at 7 carats to 13.4 × 10.3 mm at 10 carats. See an 8 carat elongated cushion on your hand.
Zendaya debuted her ring from Tom Holland in January 2025. It is reported as an elongated cushion cut diamond of about 5 carats, set east-west and attributed to British jeweler Jessica McCormack. E! News linked it to a 5.02 carat east-west cushion design by the jeweler, and The Diamond Collective describes an approximately 5 carat elongated cushion. The couple has not confirmed the details.
At 5 carats an elongated cushion measures about 10.7 × 8.2 mm. Because the stone is set east-west, its 10.7 mm length runs across the finger rather than along it, which makes it look wider on the hand than the same stone set lengthwise. Find Me Diamond draws it lengthwise, so picture it turned sideways. See a 5 carat elongated cushion on your hand.
Benny Blanco proposed in December 2024 with a marquise cut solitaire on a yellow gold pave band. Estimates vary more than for any other ring here. Jewelers quoted by National Jeweler ranged from 4 to 9 carats, including a Jared executive's estimate of 6 carats, while The Diamond Collective lists it at about 3 carats.
At 6 carats a marquise measures about 18.2 × 9.1 mm. At 3 carats it would be about 14.4 × 7.2 mm, and at 9 carats about 20.8 × 10.4 mm. The marquise is the longest shape for its weight, so even the lower estimates make a long stone. See a 6 carat marquise on your hand.
Justin Bieber proposed in 2018 with an oval solitaire made by Jack Solow of Solow & Co. It is usually reported at 6 to 10 carats, the range given by HELLO! and The Diamond Collective.
At 8 carats, the middle of that range, an oval measures about 15.4 × 11.4 mm. At 6 carats it would be about 14.0 × 10.4 mm, and at 10 carats about 16.6 × 12.3 mm. See an 8 carat oval on your hand.
Prince Harry designed the ring himself for their 2017 engagement. The cushion cut center diamond comes from Botswana and sits between two smaller diamonds from the collection of his mother, Diana, Princess of Wales. HELLO! reported an expert estimate of 2.5 to 3 carats for the center stone, and The Diamond Collective lists about 3 carats.
At 3 carats a cushion measures about 7.9 × 7.9 mm, and at 2.5 carats about 7.5 × 7.5 mm, the smallest center stone on this list. See a 3 carat cushion on your hand.
Kanye West proposed in October 2013 with a ring by Lorraine Schwartz. A representative for the jeweler told E! News it was a 15 carat cushion cut diamond, and HELLO! and The Diamond Collective report the same weight.
A 15 carat cushion measures about 13.6 × 13.6 mm. On a US size 6.5 finger, 16.9 mm across, that square outline would cover about 80 percent of the finger's width. See a 15 carat cushion on your hand.
Ryan Reynolds proposed in 2012 with a light pink oval diamond by Lorraine Schwartz, set in rose gold. It is most often reported at about 12 carats, the figure given by The Diamond Collective and repeated by InStyle and PureWow, though InStyle notes that some reports from 2012 put it at 7 to 10 carats.
At 12 carats an oval measures about 17.6 × 13.0 mm. At 7 carats it would be about 14.7 × 10.9 mm. Color does not change the size, so the same outline applies to a white or a colored diamond. See a 12 carat oval on your hand.
Jay-Z proposed in 2007 with an emerald cut diamond by Lorraine Schwartz. HELLO! reports an expert estimate of about 18 carats, and The Diamond Collective gives an estimated range of 18 to 24 carats.
An 18 carat emerald cut measures about 18.3 × 13.1 mm, the heaviest stone on this list; at 24 carats it would be about 20.2 × 14.4 mm. See an 18 carat emerald cut on your hand.
Prince Rainier III of Monaco gave Grace Kelly a Cartier ring set with an emerald cut diamond soon after their engagement was announced in January 1956. It is the most consistently reported stone here: HELLO! gives 10.47 carats, The Diamond Collective 10.48 carats, and Wikipedia rounds it to 10.5 carats.
At 10.47 carats an emerald cut measures about 15.3 × 10.9 mm. See a 10.47 carat emerald cut on your hand.
For comparison, a 1 carat round is 6.5 mm across and a 2 carat round is 8.2 mm. Because a diamond gains weight in all three dimensions, even the biggest stones here are not as large as their carat numbers suggest. An 18 carat emerald cut weighs 18 times as much as a 1 carat emerald cut but is only about 2.6 times as long: 18.3 mm against 7.0 mm.
That is also why a famous ring can look enormous in photos and more modest in person. Photos are taken close up, often with the hand turned toward the camera, and perspective exaggerates the stone. Seeing the outline at true scale on your own screen is a far better guide.
Open any link above, or go to Find Me Diamond and choose Ring. Pick the shape and type the carat weight, then set your ring size so the finger is drawn at your width. For exact physical size, hold a bank card, which is 85.6 mm wide, against the calibration bar and adjust it until the two match.
A famous ring is a good starting point for choosing a shape, even if the weight you choose is very different. The same outline at 1 to 3 carats keeps the character of the ring at an everyday scale.
Each shape has its own guide with a full carat to millimeter chart: elongated cushion, oval, marquise, cushion and emerald. For a single weight, see how big a 1 carat, 2 carat, 3 carat or 5 carat diamond is.
When you know the shape and size you want, browse lab grown diamond engagement rings. Every Ronora center stone is a real lab grown diamond with an Excellent cut, VVS clarity and D-E-F colorless, made to order in Surat, India.
It is widely reported as an elongated old mine cut diamond, an antique style cushion shape, with jewelers estimating 7 to 10 carats. Sized as a modern elongated cushion, 8 carats is about 12.5 × 9.6 mm.
By reported weight, Beyoncé's emerald cut, estimated at about 18 carats or more, which is about 18.3 × 13.1 mm. By length a marquise can come close: at the estimated 6 carats, Selena Gomez's marquise would be about 18.2 mm long.
A 15 carat cushion, the reported weight of Kim Kardashian's 2013 ring, measures about 13.6 × 13.6 mm. A 15 carat round would be about 16.0 mm across.
No. They are estimates for well proportioned stones of the reported weight at the classic ratio for each shape. The real stones may be cut longer, deeper or shallower, and most of the carat weights are themselves estimates made from photographs.
