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Choose by millimetres, not carats. A carat figure on moissanite describes how large a one-carat diamond looks, not what the stone weighs, so the width in millimetres is the only number that tells you how big the earring will be on your ear.
Our moissanite stud earrings come in five widths: 3 mm, 4 mm, 6 mm, 6.5 mm and 8 mm. If you want one pair for daily wear, 6 mm or 6.5 mm is where most people land. If you want something quiet or a second piercing, 3 mm or 4 mm. If you want the earrings to be noticed from across a room, 8 mm.
The rest of this article explains why millimetres are the honest measure, what each size looks like on an ear, and what holds the earring on. It is written for someone choosing a pair, so it concedes the awkward parts as well as the good ones.
Why are moissanite earrings sold in millimetres?
Diamonds are sold by weight, and carat is a unit of weight. Moissanite is a different material, silicon carbide, and it is less dense. GIA gives the specific gravity of diamond as 3.52 and moissanite as 3.22, so a moissanite stone of a given width weighs a little less than a diamond of the same width.
Sellers get around this with diamond equivalent weight. A moissanite labelled one carat is cut to the same millimetre width as a one-carat diamond, so the two look the same size when worn. Carat figures for moissanite describe the visual size of an equivalent stone, not its weight.
That is useful, but only if every seller uses the same chart, and they do not always. Millimetres have no such ambiguity. We list widths in millimetres for exactly that reason, and our earlier piece on what 1ct, 2ct and 3ct moissanite look like worn covers the carat labels in more detail.
What size moissanite studs look right on an ear?
The photograph below puts four widths on four ears at the same scale. The step from 4 mm to 6 mm is the one most people underestimate. At 6 mm the stone stops being a point of light and becomes a visible shape.
| Width | How it reads | Typical carat label | Suits |
|---|---|---|---|
| 3 mm | A small point of light | Varies by seller | Second or third piercing |
| 4 mm | Understated, still visible | Varies by seller | First piercing kept quiet, or stacking |
| 6 mm | Reads clearly from across a room | Varies by seller | One everyday pair |
| 6.5 mm | Reads clearly, slightly fuller | About 1 ct | One everyday pair |
| 8 mm | Unmistakable | About 2 ct | When the stone is the statement |
A 6.5 mm round stone is the size sold as one carat. Only that and the 8 mm figure are widely agreed, which is why the other rows say that labels vary. We would rather leave a cell honest than fill it with a number we cannot stand behind.
A photograph also cannot give you your own ear. Lobe size varies a good deal, and the same 6 mm stone will look larger on a small lobe than a large one. If you are between two sizes, the smaller is the easier one to live with, and most people buying one everyday pair choose 6 mm or 6.5 mm.
Is bigger always better for moissanite studs?
No. A larger stone shows more of the fire moissanite is known for, because it disperses light more strongly than diamond. But it is also more noticeable in everyday wear, and it makes the earring the focus of the whole outfit.
Smaller stones have a real advantage: they stack. A 3 mm beside a 4 mm, or a small stone alongside a larger one in a second hole, looks deliberate. Pairing sizes is easier to do going up from small than down from large.
What about a flower cluster instead of a single stone?
A cluster solves a different problem. Our flower cluster studs use seven round stones, one larger at the centre ringed by six, and the whole blossom measures 7.2 mm across. Seven crowns catch light at seven angles, so a cluster shows more movement than a single stone of the same width.
The trade-off is that you see a flower and not a solitaire. If you want the classic single stone, choose the solitaire. If you want something that reads as finished with one pair and nothing else, the cluster does that.
What backing should moissanite studs have?
This is the part that decides whether you keep the earrings. The stone is rarely what fails. The post and back are.
Our studs use a straight post with a push-on butterfly back. It is quick to fit and sits flat behind the lobe, but it holds by friction alone, and jewellers generally rate it as the least secure of the common types. That is fine for lightweight everyday studs. It is less reassuring for the larger sizes or for anyone who sleeps in their earrings.
Locking backs, sometimes called La Poussette backs, and screw backs are generally rated more secure. If you want that extra margin, you can fit one yourself, though you should check it fits the diameter of the post. The post and back decide whether an earring stays on your ear, not the stone.
Replace a back that has gone loose, since a back that no longer grips is the weak point in any friction fit.
Which finish should you choose?
Both are 925 sterling silver with a protective plating. Yellow-gold plating sits warm against the skin, and white-gold plating reads cooler and closer to silver-toned chains and watches. The plating is a coating, so it will eventually wear and can be renewed, as we explain in our guide to how long rhodium plating lasts.
If you are unsure whether a stone will look right to others, how to tell moissanite from a diamond by eye explains what the stone does, and what it does not claim to be. Moissanite is silicon carbide and we sell it as that. The stones are laboratory-grown, and a gemstone certificate ships with the pair.
Moissanite earrings and matching pieces
Earrings sit well with a single-stone necklace, and a set of two or three pieces makes a straightforward gift. If you are buying for someone else, our piece on jewellery gifts that do not look cheap sets out what to check.
Moissanite stud earringsfive widths from 3 mm to 8 mm, in yellow-gold or white-gold plating
Flower cluster studsseven stones in one blossom, 7.2 mm across
Floating solitaire necklacea single stone to match a single-stone earring
Moissanite eternity bandstones all the way round, in three stone sizes
Moissanite tennis braceleta continuous line of stones, three widths
Moissanite cross pendantone size, in gold or rhodium tone
You can browse the full range by category — rings, earrings, bracelets and necklaces — or start with our best sellers.
Common questions
What size moissanite stud earrings should I buy?
For everyday wear most people choose 6 mm or 6.5 mm, which read clearly without dominating. Choose 3 mm or 4 mm for a second or third piercing or a quieter look, and 8 mm if you want the stone to be the first thing noticed.
Is a 1 carat moissanite stud 6.5 mm?
Usually, yes. A 6.5 mm round stone is the size sold as one carat, because moissanite is sized to match a one-carat diamond in millimetres. The carat figure is a visual equivalent rather than the weight of the stone, and sellers do not all label the smaller sizes the same way.
Why do moissanite earrings sometimes weigh less than a diamond pair?
Moissanite is less dense than diamond, with a specific gravity of about 3.22 against 3.52, so a stone of the same millimetre size weighs a little less. That is why it is sold by diamond-equivalent size and not by its own weight.
Are push-back earring backs secure enough?
They are the least secure common type, because they hold by friction alone and can loosen over time. For lightweight everyday studs they are normal, but locking and screw backs are generally rated more secure if you want extra assurance.
Do moissanite stud earrings suit a second piercing?
Yes, the smaller widths are the usual choice. A 3 mm or 4 mm pair sits neatly above or beside a larger stone, and a graduated stack in one finish looks deliberate.
More questions
We answer shipping, returns, sizing and payment questions on our FAQ page. If something is not covered there, get in touch and a person from the workshop will answer.
References
The density figures (specific gravity of about 3.52 for diamond and 3.22 for moissanite) are as published by the Gemological Institute of America and reported in trade coverage of its laboratory findings. Round-stone millimetre sizes for diamond-equivalent weight, including 6.5 mm for one carat and 8 mm for two carats, are drawn from published seller sizing charts, which agree on those two figures but differ on others. Observations about earring backs reflect the consensus of published jeweller guides. Stone widths and setting details for our own pieces are taken from the product listings.
