Moissanite Size Chart: MM to Carat Equivalent for Round, Oval, Pear & Cushion Cuts

Moissanite MM to Carat Equivalent: Quick Chart

MM, Carat and DEW: What Is the Difference?

Millimetres (mm)

Millimetres describe physical dimensions. For a round stone, the key measurement is diameter. For elongated shapes, you normally see length × width, such as 8 × 6 mm.

Carat

Carat is weight. One carat equals 0.2 grams. It does not directly tell you how wide a gemstone looks.

DEW — Diamond Equivalent Weight

DEW is a comparison term used to communicate how large a moissanite looks relative to a diamond of similar dimensions.

It is not the actual weight of the moissanite.

Round Moissanite Size Chart

Round is the easiest shape to compare because diameter is the main face-up measurement.

Oval Moissanite Size Chart

Oval stones need two measurements because length-to-width ratio changes the shape and the visual spread.

An elongated oval can look larger on the finger than a round stone with similar diamond-equivalent weight because it covers more finger length.

Pear Moissanite Size Chart

Pear cuts combine a rounded end with a pointed tip. Their apparent size changes noticeably with length-to-width ratio.

Charles & Colvard product specifications illustrate why millimetres matter: pear moissanite in 8 × 5 mm and 10 × 7 mm sizes can be marketed around roughly 1 ct and 2.1 ct DEW respectively, while the stones' actual mass is a separate measurement.

Cushion Moissanite Size Chart

Cushion cuts vary more than round cuts because some are square, some elongated, and facet patterns differ between brands.

As a real-world reference, Charles & Colvard lists a 6 mm cushion around 1.1 ct DEW, a 7.5 mm cushion around 2 ct DEW and an 8 mm cushion around 2.4 ct DEW.

Why Two “1 Carat” Moissanite Stones Can Look Different

There are several reasons:

• One seller may mean actual carat weight while another means DEW.
• The shapes may be different. A long oval spreads differently from a round stone.
• Cut depth varies. More weight can be hidden below the girdle rather than visible from the top.
• Length-to-width ratio changes face-up area.
• Brands round their DEW values differently.

This is why the most useful buying question is not “How many carats?” but “What are the exact millimetre dimensions?”

Actual Moissanite Weight vs Diamond Equivalent Weight

Never assume a certificate or listing that says “1 ct” automatically means actual stone weight. Look for words such as DEW, diamond equivalent, carat equivalent, stone dimensions or actual weight.

Which Measurement Matters Most When Buying Online?

For appearance, millimetres are the most useful measurement.

If you are deciding whether a ring will look delicate or dramatic, the face-up dimensions tell you more than the carat label. For an oval, pear or elongated cushion, always read both length and width.

How Shape Changes the Visual Size

Round

Compact and symmetrical. Diameter gives a very clear idea of visual size.

Oval

Usually covers more finger length than a round stone of similar DEW, so it can look larger.

Pear

The pointed end creates extra length, giving the stone a more elongated face-up presence.

Cushion

Can look compact or elongated depending on ratio and corner shape. Do not judge cushion size from one number unless it is truly square.

What Is Length-to-Width Ratio?

Length-to-width ratio is simply length divided by width.

For example:

• An 8 × 6 mm oval has a ratio of about 1.33.
• A 9 × 6 mm pear has a ratio of 1.50.
• An 8 × 8 mm cushion has a ratio of 1.00 and is square.

Higher ratios create a more elongated look. Two stones can have similar DEW yet appear very different because one is long and narrow while the other is wider.

What Size Moissanite Looks Like a 1 Carat Diamond?

Useful starting points are:

• Round: about 6.5 mm
• Oval: about 7 × 5 mm, although some brands use larger dimensions for a 1 ct visual target
• Pear: around 8 × 5 mm
• Cushion: around 6 mm

These are visual equivalents, not a rule that every stone with those measurements has the same actual weight.

What Size Moissanite Looks Like a 2 Carat Diamond?

Approximate starting points:

• Round: about 8 mm
• Oval: around 9 × 7 mm
• Pear: around 10 × 7 mm
• Cushion: around 7.5 mm

Does a Bigger Moissanite Always Look Better?

No. Size changes the balance of the entire piece.

Consider:

• Finger width
• Band width
• Setting height
• Halo or side stones
• Daily activities
• Whether you prefer subtle or statement jewellery

A 6.5 mm round solitaire can look substantial on one hand and delicate on another. Use millimetres to compare stones, then consider the complete setting.

Moissanite Size for Earrings and Pendants

The same dimensions can feel much larger in earrings or pendants than in a ring because there is less surrounding visual information.

For stud earrings, remember that quoted total carat equivalent may represent both earrings combined. A pair sold as 1 ct total DEW may contain roughly 0.5 ct DEW per ear.

For pendants, millimetres are again the easiest way to judge how noticeable the centre stone will look from normal viewing distance.

Real Moissanite Examples at Jewelry Towns

Round Moissanite Pendant Necklace

Available in 0.5 ct, 1.0 ct and 1.5 ct listed options

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Solitaire Moissanite Ring

1.5 ct listed centre · 925 sterling silver

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Square Halo Moissanite Jewellery Set

Ring, necklace, studs or full set

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Shop: Rings · Necklaces · Earrings · Bracelets

Frequently Asked Questions