Moissanite jewelry on soft champagne fabric

Moissanite MM to Carat Guide

Compare approximate millimeter dimensions and carat-equivalent sizes across popular moissanite shapes.

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Updated: September 26, 2026

Guidance you can trust: CelinieJourney is committed to making every step of your jewelry journey clear and effortless. This guide brings together shape-specific millimeter and carat-equivalent references so you can compare visual proportions with greater confidence. Because dimensions can vary with an individual stone’s cut and proportions, confirm the exact measurements on the product page before choosing your piece.

Understanding Moissanite MM and Carat

Millimeters measure a moissanite stone’s visible dimensions, while carat is a unit of weight. In jewelry listings, carat-equivalent language offers a familiar size reference, but it does not replace the actual millimeter measurement.

Two stones with the same carat-equivalent label can look different because their shape and proportions distribute material differently. Use the millimeter dimensions to compare the face-up size, then visit our Moissanite Carat Guide for visual-scale and setting context.

Loose moissanite stones in different shapes

Moissanite Size Conversion by Shape

Moissanite millimeter-to-carat conversions are approximate rather than exact. The charts below compare estimated millimeter dimensions with carat-equivalent weights across the shapes in our collection. Round, cushion, princess, asscher, heart, trillion, and orchid use a single millimeter measurement, while radiant, pear, marquise, emerald, and oval are listed as length by width because their proportions affect their visible spread.

For help visualizing moissanite sizes, visit one of our showrooms, book a virtual appointment, or chat live on our website for assistance.

Radiant MM to Carat Weight Moissanite Size Chart

Radiant moissanite has a bright, geometric outline; compare millimeter dimensions to understand its face-up spread. Shop Radiant Cut Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
4.4 x 3.1 mm 0.25 ct
5.6 x 4 mm 0.50 ct
6.4 x 4.5 mm 0.75 ct
7 x 5 mm 1.00 ct
7.5 x 5.4 mm 1.25 ct
8 x 5.7 mm 1.50 ct
8.8 x 6.3 mm 2.00 ct
10.1 x 7.2 mm 3.00 ct

Asscher MM to Carat Weight Moissanite Size Chart

Asscher moissanite is square with clipped corners, so a single millimeter measurement offers a useful visual-size reference. Shop Asscher Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
3.5 mm 0.25 ct
4.4 mm 0.50 ct
5 mm 0.75 ct
5.5 mm 1.00 ct
5.9 mm 1.25 ct
6.3 mm 1.50 ct
6.9 mm 2.00 ct
7.9 mm 3.00 ct

Princess MM to Carat Weight Moissanite Size Chart

Princess moissanite has a compact square outline; millimeter dimensions help compare its visible scale. Shop Princess Cut Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
3.5 mm 0.25 ct
4.4 mm 0.50 ct
5 mm 0.75 ct
5.5 mm 1.00 ct
5.9 mm 1.25 ct
6.3 mm 1.50 ct
6.9 mm 2.00 ct
7.9 mm 3.00 ct

Pear MM to Carat Weight Moissanite Size Chart

Pear moissanite uses length and width measurements because its elongated silhouette changes visual coverage. Shop Pear Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
5.4 x 3.5 mm 0.25 ct
6.7 x 4.4 mm 0.50 ct
7.7 x 5 mm 0.75 ct
8.5 x 5.5 mm 1.00 ct
9.2 x 5.9 mm 1.25 ct
9.7 x 6.3 mm 1.50 ct
10.7 x 6.9 mm 2.00 ct
12.3 x 7.9 mm 3.00 ct

Round MM to Carat Weight Moissanite Size Chart

Round moissanite has straightforward size comparisons because its uniform diameter is measured with one number. Shop Round Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
4.1 mm 0.25 ct
5 mm 0.50 ct
5.8 mm 0.75 ct
6.5 mm 1.00 ct
6.9 mm 1.25 ct
7.5 mm 1.50 ct
8 mm 2.00 ct
9 mm 3.00 ct

Marquise MM to Carat Weight Moissanite Size Chart

Marquise moissanite uses length and width measurements, which shape its long, tapered visual spread. Shop Marquise Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
6.3 x 3.1 mm 0.25 ct
7.9 x 4 mm 0.50 ct
9.1 x 4.5 mm 0.75 ct
10 x 5 mm 1.00 ct
10.8 x 5.4 mm 1.25 ct
11.4 x 5.7 mm 1.50 ct
12.6 x 6.3 mm 2.00 ct
14.4 x 7.2 mm 3.00 ct

Emerald MM to Carat Weight Moissanite Size Chart

Emerald cut moissanite is measured by length and width, helping you compare its rectangular visual proportions. Shop Emerald Cut Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
4.4 x 3.1 mm 0.25 ct
5.6 x 4 mm 0.50 ct
6.4 x 4.5 mm 0.75 ct
7 x 5 mm 1.00 ct
7.5 x 5.4 mm 1.25 ct
8 x 5.7 mm 1.50 ct
8.8 x 6.3 mm 2.00 ct
10.1 x 7.2 mm 3.00 ct

Cushion MM to Carat Weight Moissanite Size Chart

Cushion moissanite has a soft-square outline; use its millimeter measurement to compare its face-up scale. Shop Cushion Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
3.8 mm 0.25 ct
4.8 mm 0.50 ct
5.5 mm 0.75 ct
6 mm 1.00 ct
6.5 mm 1.25 ct
6.9 mm 1.50 ct
7.6 mm 2.00 ct
8.7 mm 3.00 ct

Oval MM to Carat Weight Moissanite Size Chart

Oval moissanite uses length and width measurements, since proportions influence how elongated it looks. Shop Oval Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
5 x 3.8 mm 0.25 ct
6.3 x 4.8 mm 0.50 ct
7.3 x 5.5 mm 0.75 ct
8 x 6 mm 1.00 ct
8.6 x 6.5 mm 1.25 ct
9.2 x 6.9 mm 1.50 ct
10.1 x 7.6 mm 2.00 ct
11.5 x 8.7 mm 3.00 ct

Heart MM to Carat Weight Moissanite Size Chart

Heart moissanite is measured by a single approximate millimeter size for an easy visual reference. Shop Heart Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
4.1 mm 0.25 ct
5 mm 0.50 ct
5.8 mm 0.75 ct
6.5 mm 1.00 ct
6.9 mm 1.25 ct
7.5 mm 1.50 ct
8 mm 2.00 ct
9 mm 3.00 ct

Trillion MM to Carat Weight Moissanite Size Chart

Trillion moissanite uses a single approximate millimeter size to compare its triangular face-up spread. Shop Trillion Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
4.1 mm 0.25 ct
5 mm 0.50 ct
5.8 mm 0.75 ct
6.5 mm 1.00 ct
6.9 mm 1.25 ct
7.5 mm 1.50 ct
8 mm 2.00 ct
9 mm 3.00 ct

Orchid MM to Carat Weight Moissanite Size Chart

Orchid moissanite is measured by a single approximate millimeter size to compare its floral outline. Shop Orchid Moissanite Jewelry
Approximate Moissanite MM Size Approximate Moissanite Carat Equivalent
3.8 mm 0.25 ct
4.6 mm 0.50 ct
5.4 mm 0.75 ct
6 mm 1.00 ct
6.4 mm 1.25 ct
6.9 mm 1.50 ct
7.4 mm 2.00 ct
8.3 mm 3.00 ct

Shop Moissanite by Shape

Radiant moissanite shapeRadiantAsscher moissanite shapeAsscherPrincess moissanite shapePrincessPear moissanite shapePearRound moissanite shapeRoundMarquise moissanite shapeMarquiseEmerald moissanite shapeEmeraldCushion moissanite shapeCushionOval moissanite shapeOvalHeart moissanite shapeHeartTrillion moissanite shapeTrillionOrchid moissanite shapeOrchid

Moissanite MM-to-Carat FAQs

Is moissanite mm to carat conversion exact?

No. A moissanite mm to carat conversion is an approximate carat-equivalent reference, not a universal physical-weight conversion. Cut, depth, shape, and proportions can change the final dimensions.

How do I use a moissanite carat to mm chart?

Use a moissanite carat to mm chart to compare visible dimensions first, then read the carat-equivalent value as a familiar size category. This moissanite size chart to carat comparison is most useful when you stay within the same shape.

How many millimeters are 1 carat, 2 carat, and 3 carat round moissanite?

For the round reference in this guide, 1 carat moissanite mm is 6.5 mm, 2 carat moissanite mm is 8 mm, and 3 carat moissanite mm is 9 mm. Check the product page for the exact stone.

How many carats is 6.5 mm moissanite?

For a round stone in this chart, 6.5 mm moissanite in carats is approximately 1.00 ct equivalent. The same 6.5 mm measurement can represent a different reference point in another shape.

What is 7.5 mm moissanite to carat?

In the round row, 7.5 mm moissanite to carat is approximately 1.50 ct equivalent. Use the shape-specific table rather than applying that reference to every silhouette.

How many carats is 8 mm moissanite?

In the round row, 8 mm moissanite in carats is approximately 2.00 ct equivalent. Oval, pear, emerald, and other elongated shapes should be compared by length and width.

What are 8.5 mm and 10mm moissanite in carats?

There is no single universal answer for 8.5 mm moissanite in carats or 10mm moissanite in carats. Match the shape and proportions to the closest supplied table row, then confirm the exact product specification.

What is the 8x6 oval moissanite carat equivalent?

In this guide, the 8x6 oval moissanite carat equivalent is approximately 1.00 ct. A 9x7 oval moissanite carat equivalent is not listed in the supplied data, so compare the actual dimensions and proportions rather than assuming one universal value; the same applies to a general 9x7 moissanite carat equivalent.

Which shape-specific moissanite mm to carat chart should I use?

Use the row that matches your outline: round moissanite mm to carat, oval moissanite mm to carat, emerald cut moissanite mm to carat, pear moissanite mm to carat, or cushion moissanite mm to carat. Each outline distributes its dimensions differently.

Why can a product page differ from a moissanite carat size chart?

A moissanite carat size chart is a comparison tool, while a product page describes one specific stone. For an mm to carat moissanite lookup, the product page remains the final source for cut, proportions, and listed dimensions.