Marquise Diamond Size Chart: Carat Weight to MM Guide

A marquise diamond has a long, narrow shape with pointed ends. Because of its shape, it can look bigger on the finger compared to some other diamond cuts of the same carat weight.

But when choosing a marquise diamond, carat weight alone is not enough. The length and width in millimetres (MM) also matter because they tell you how large the diamond will actually look from the top.

What Is a Marquise Diamond?

A marquise diamond has an elongated shape with curved sides and two pointed ends. Its long outline gives it a distinctive appearance and can also make the finger look more elongated.

Marquise Diamond Carat to MM Size Chart

Here is a general guide to help you understand how carat weight compares with the approximate size of a marquise diamond:

These measurements are approximate. The exact size can be different from one diamond to another, even when they have the same carat weight.

What Does 10 × 5 MM Mean?

If a marquise diamond is listed as 10 × 5 mm, it means:

• 10 mm is the length, measured from one pointed end to the other.

• 5 mm is the width, measured across the widest part of the diamond.

So, a 10 × 5 mm marquise diamond has a long and narrow appearance.

Is a 1-Carat Marquise Diamond Big?

A 1-carat marquise diamond is usually around 10 × 5 mm.

It can look quite noticeable because the marquise shape spreads the diamond across a longer area of the finger. This means a 1-carat marquise may appear larger than you expect when compared with a round diamond of the same weight.

However, the actual appearance still depends on the diamond's proportions and cut.

What About a 2-Carat Marquise Diamond?

A 2-carat marquise diamond is generally around 13 × 6.5 mm.

This gives it much more finger coverage than a 1-carat stone and makes the centre diamond more prominent in the ring.

Two 2-carat marquise diamonds can still look slightly different if their length, width and depth are different.

Carat Weight vs MM Size

It is important to understand that carat and size are not the same thing.

Carat measures the weight of the diamond, while millimetres show its physical dimensions.

For example, two diamonds can both weigh 1 carat but have slightly different measurements. One may be longer and slimmer, while the other may be shorter and wider.

That is why checking the MM measurements is useful when you want to know how much space the diamond will cover on your finger.

Why Does the Shape of a Marquise Matter?

Not every marquise diamond has exactly the same outline.

A wider marquise can have a fuller appearance, while a longer and narrower marquise gives a more stretched-out look.

This is why two diamonds with the same carat weight can still look different when worn.

How to Choose the Right Marquise Diamond Size

Your choice depends on the look you want from your jewellery.

0.25 to 0.75 carat:
Suitable for a smaller centre stone, everyday jewellery or designs where the marquise is combined with other diamonds.

1 to 1.5 carat:
A good range if you want the marquise shape to be clearly visible without choosing a very large stone.

2 carat and above:
Better suited to a larger centre-stone look with more coverage across the finger.

Should You Choose Carat or MM Size?

Ideally, look at both.

Carat weight tells you how much the diamond weighs, while MM measurements give you a better idea of how large it will look.

When comparing marquise diamonds, check:

• Carat weight

• Length

• Width

• Depth

• Overall proportions

• Cut quality

This gives you a better idea of the diamond's actual appearance than carat weight alone.

Final Thoughts

A marquise diamond can give your ring a distinctive look because of its long shape and pointed ends. But choosing the right size is not just about picking a higher carat weight.

Use the carat-to-MM chart as a starting point, then check the actual measurements of the diamond you are considering. This will help you understand how much space the stone will cover and whether its shape matches the look you want.

Remember: Carat tells you how much the diamond weighs, while MM tells you how large it is. For a marquise diamond, both measurements are important.