Celebrity Inspired
Serena Williamsβs Engagement Ring: The Oval with Half-Moon Side Stones
Why half moons are the side stone that makes an oval look bigger β and what to check so they sit perfectly flush.
Written by the Mapple Gems workshop, Surat Β· Updated 26 September 2026
Short answer: Serena Williamsβs engagement ring from Alexis Ohanian, given in December 2016, was a three-stone ring: a large oval diamond flanked by two half-moon diamonds, commonly described in platinum. The centre is most often estimated at about 12 carats, with some estimates higher; she has since been seen wearing a reworked version. Our inspired version is an oval moissanite or IGI-certified lab grown diamond with half-moon side stones, 2 to 5 carats.
Alexis Ohanian proposed in December 2016 at the Cavalieri Hotel in Rome β at the same spot where the two had met by chance a year and a half earlier. Serena Williams announced it in a post on Reddit, the company Ohanian co-founded. The couple married in New Orleans in 2017.
The original ring put a big oval centre between two half-moon side stones. Estimates for the centre usually sit around 12 carats, with some as high as 17; none has been confirmed. More recent coverage notes that the ring she wears today appears to have no side stones and a pavΓ© band, which suggests it has been reset. This guide is about the original three-stone look.
What a half moon does that other side stones do not
A half moon is shaped like a round stone cut in half: one straight edge and one curved. The straight edge sits against the centre stone and the curve faces outward, so the three stones together read as one continuous, rounded shape β almost like a single larger oval. That is why half moons make a centre look bigger than tapered baguettes or pears of the same weight. Most half moons are step-cut, which also contrasts the ovalβs sparkle with calmer flashes at the sides.
The original compared with our inspired version
| Williamsβs original ring (as reported) | Mapple Gems inspired version | |
|---|---|---|
| Centre stone | Oval diamond | Oval moissanite or lab grown diamond |
| Size | Unconfirmed; commonly ~12ct | 2, 3, 4 or 5 carats |
| Side stones | Two half moons | Two half moons |
| Metal | Commonly reported as platinum | 925 silver or solid 10K/14K/18K yellow, rose or white gold |
| Paperwork | Not public | IGI certificate with lab grown; moissanite is not graded |
Moissanite or lab grown diamond?
Moissanite (silicon carbide, dispersion 0.104) suits this design well: step-cut half moons show little of moissaniteβs coloured fire, so the sides stay calm while the oval sparkles. Lab grown diamond (Mohs 10, dispersion 0.044) is the closest match to the original and includes an IGI certificate for the centre; like all fancy shapes, the oval has no cut grade, so judge its bow-tie on video. In a three-stone ring the stones sit side by side, so a well-matched set looks better than a top-colour centre beside warmer sides.
From the workshop
The straight edge of each half moon has to meet the curve of the oval with no visible gap, and an ovalβs curve is different at every point along its side. So half moons are matched to a particular centre stone, not bought off a shelf by size. When ordering any half-moon ring, ask for the millimetre length of the straight edge on each side stone compared with the height of the oval at that point, and for a close-up from above before setting. A gap you can see in a photograph will catch dirt and read as a gap on the hand.
Before you order
- Ask for the total width across all three stones β half-moon rings can be wider than you expect.
- Ask for the side stonesβ measurements and how they meet the oval.
- Choose a length-to-width ratio for the oval around 1.35 to 1.45 so the three stones form a balanced shape.
- Plan a contoured wedding band; three-stone rings rarely sit flush with a straight one.
Keep reading
Frequently asked questions
What does Serena Williamsβs engagement ring look like?
Her original ring was a three-stone design with a large oval diamond between two half-moon side stones. More recent photos suggest it has been reset without side stones.
How many carats is Serena Williamsβs ring?
It has not been confirmed. The centre is most often estimated at about 12 carats, with some estimates up to 17.
Where did Alexis Ohanian propose?
At the Cavalieri Hotel in Rome in December 2016, where the couple had first met.
What are half-moon side stones?
Side stones shaped like half a round, with a straight edge against the centre stone and a curved outer edge. They make the three stones read as one larger rounded shape.
Is moissanite good for a three-stone oval ring?
Yes. Moissanite is Mohs 9.25 and suits daily wear, and step-cut half moons show little extra fire. It is not a diamond and is not laboratory graded.
The oval and half-moon three-stone, made to order
2 to 5 carat centres, silver to 18K gold.
In moissanite In lab grown diamondMapple Gems is an independent workshop in Surat, India, and is not affiliated with, sponsored by or endorsed by Serena Williams or Alexis Ohanian. βInspiredβ describes a design reference, not a copy. Details of the original ring come from published reporting; carat and price figures in the press are estimates.
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