Moissanite & lab diamond engagement rings crafted to last a lifetime.

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Diamond VS. Moissanite

Carat Size Equivalents

Diamonds are measured by carat, which indicates their weight. However, moissanites do not weigh the same as diamonds - making it difficult to make exact comparisons between the carat weight of a diamond and the equivalent size of a moissanite.

Therefore, we highly recommend that you consider our stone measurements in millimeters when choosing your stone size, rather than going by carat weight. 

Please see the below charts for comparisons between moissanite size (in mm) and the approximate equivalent diamond carat weight. Millimeter measurements are listed as length x width.

Note: We can cut any size moissanite for you - even if it's not listed in these charts!

Round

Round

mm Approximate Carat Equivalent
5 x 5 0.5
5.5 x 5.5 0.63
6 x 6 0.8
6.5 x 6.5 1
7 x 7 1.2
7.5 x 7.5 1.5
8 x 8 2
8.5 x 8.5 2.5
9 x 9 3
9.5 x 9.5 3.5
10 x 10 4
10.5 x 10.5 4.5
11 x 11 4.9
Round

Oval

Oval

mm Approximate Carat Equivalent
7 x 5 0.9
8 x 6 1.5
9 x 6 1.8
9 x 6.5 1.9
9 x 7 2
9.5 x 7 2.25
10 x 7 2.5
10 x 7.5 2.75
10 x 8 3
10.5 x 8 3.25
11 x 8 3.5
11 x 8.5 3.9
11 x 9 4.2
12 x 9 5
12 x 10 5.8
13 x 10 6.5
Oval

Pear

Pear

mm Approximate Carat Equivalent
7 x 5 0.77
8 x 5 1
9 x 6 1.5
9 x 7 1.8
10 x 7 2.1
10 x 8 2.5
11 x 7.5 2.7
11 x 8 3
12 x 8 3.2
12 x 8.5 3.8
12 x 9 4
13 x 9 4.7
14 x 9.5 5.6
Pear

Cushion

Cushion

mm Approximate Carat Equivalent
5 x 5 0.6
5.5 x 5.5 0.8
6 x 6 1.1
6.5 x 6.5 1.3
7 x 7 1.7
7.5 x 7.5 2
8 x 8 2.4
8.5 x 8.5 3
9 x 9 3.3
9.5 x 9.5 4.2
10 x 10 5
Cushion

Elongated Cushion

Elongated Cushion

mm Approximate Carat Equivalent
7 x 6 1.3
8 x 6 1.6
8 x 6.5 1.8
8 x 7 2
8.5 x 7 2.2
9 x 7 2.4
9 x 7.5 2.5
9 x 8 2.6
9.5 x 8 2.9
10 x 8 3.2
10 x 9 3.6
11 x 9 5
11 x 10 5.7
12 x 9 5.7
12 x 10 6.5
Elongated Cushion

Radiant

Radiant

mm Approximate Carat Equivalent
6 x 4 0.7
7 x 5 1.2
8 x 6 1.8
9 x 6 2.3
9 x 7 2.7
10 x 7 3.3
10 x 8 3.9
11 x 8 4.8
11 x 9 5.3
11.5 x 9 5.6
12 x 9.5 6.2
12.5 x 9 6.1
12.5 x 10 7
Radiant

Emerald

Emerald

mm Approximate Carat Equivalent
6 x 4 0.7
6.5 x 5 1
7 x 5 1.2
7.5 x 5.5 1.5
8 x 6 1.8
8.5 x 6 2
9 x 6 2.3
9 x 7 2.7
9.5 x 7 3
10 x 7 3.3
10 x 8 3.9
11 x 8 4.8
11 x 9 5.3
emerald stone

Asscher

Asscher

mm Approximate Carat Equivalent
5 x 5 0.6
5.5 x 5.5 0.8
6 x 6 1
6.5 x 6.5 1.3
7 x 7 1.5
7.5 x 7.5 2
8 x 8 2.5
8.5 x 8.5 3
9 x 9 3.5
9.5 x 9.5 4
10 x 10 5
Asscher

Princess

Princess

mm Approximate Carat Equivalent
5 x 5 0.6
5.5 x 5.5 0.8
6 x 6 1
6.5 x 6.5 1.3
7 x 7 1.5
7.5 x 7.5 2
8 x 8 2.5
8.5 x 8.5 3
9 x 9 3.5
9.5 x 9.5 4
10 x 10 5
Princess

Heart

Heart

mm Approximate Carat Equivalent
6 x 6 0.8
6 x 7 1
6.5 x 6.5 1
7 x 7 1.2
7 x 8 1.4
7.5 x 6.5 1.2
7.5 x 7.5 1.4
8 x 8 1.9
8 x 9 2.3
8.5 x 8.5 2.3
8.5 x 9.5 2.6
9 x 9 2.6
9 x 10 3.1
9.5 x 9.5 3.1
10 x 10 3.5
Heart

Marquise

Marquise

mm Approximate Carat Equivalent
8.2 x 4.3 0.5
10.2 x 5.3 1
11.7 x 6.1 1.5
12 x 6.5 1.8
13 x 6.8 2
13.3 x 7 2.3
13.77 x 7.25 2.5
14.25 x 7.5 2.75
15.2 x 8 3.25
15.7 x 8.25 3.5
16.15 x 8.5 4
17.1 x 9 4.5
Marquise

Why Choose Moissanite?

Moissanite is extremely clear, sparkly, virtually flawless - all at a very reasonable price. It is superior to diamonds in terms of brilliance and sparkle and is the second-hardest gemstone in the world. This makes it perfectly durable for everyday wear and can be passed down through generations.

Moissanite is truly the best fit for your modern love story.

Can you see the difference between
moissanites and diamonds?

It is not easy to tell diamonds apart from moissanites when simply looking with the naked eye.

Even to highly experienced jewelers, it can be very challenging to tell the difference without the use of specialized equipment. We have visited several jewelers who were surprised to learn that our moissanites were not actually diamonds. Only upon inspecting our stones closely, in specific lighting and with a magnifier, could they tell that they were not diamonds.

Our moissanite is expertly cut by artisans with over 15 years experience. The result is a beautiful, sparkly and clear stone. In reality, the vast majority of people would not be able to tell our moissanite apart from a diamond.

To get the most diamond-like look, we highly recommend you choose our classic round moissanite. It comes in a hearts & arrows cut, which is expertly cut to sparkle and shine very similarly to a diamond. It is beautiful!

What is
The Castlefield Cut™?

Castlefield Collection creates the most beautiful moissanite you'll ever see. Using only premium materials, our moissanite stones are cut to maximize their diamond-like clarity and sparkle - this is called the Castlefield Cut™. Even jewellers have a difficult time telling our moissanite apart from diamonds!

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Try our FREE

Stone Size Stickers

Not sure which stone shape or size will suit you best?

Use our stickers to try on a variety of stone shapes in a wide array of sizes! Then, you can be sure you're choosing the size that works best for your hand and finger size.

We'll even cover the shipping cost!