A marquise cut is a long, narrow shape with pointed ends, said to have been commissioned to resemble the smile of a French noblewoman. It has come back into real fashion over the past several years, prized for one specific advantage no other cut matches as well.
Marquise Diamond Size Chart: MM to Carat
| Carat Weight | Approximate MM Size (Length x Width) |
|---|---|
| 0.50 ct | 9.0mm x 4.5mm |
| 0.75 ct | 10.3mm x 5.2mm |
| 1.00 ct | 11.2mm x 5.6mm |
| 1.50 ct | 12.8mm x 6.4mm |
| 2.00 ct | 14.0mm x 7.0mm |
Figures assume a standard length to width ratio near 2 to 1. An IGI certificate confirms a specific stone's actual measurements.
The Biggest Looking Carat for Carat Diamond Shape
Because a marquise spreads its surface area across an elongated outline, it consistently reads as the largest looking shape for a given carat weight, larger even than an oval or pear. For buyers focused on visual size within a set budget, it is the most efficient cut available.
Watch for the Bow Tie Effect
Like ovals and pears, marquise cuts can show a bow tie shadow across the centre. A well cut stone minimises this to a soft shading rather than a dark, distracting band, and it is worth checking under real light before buying.
Best Settings for a Marquise Diamond
A five prong setting, with points protected at both tips, is the standard secure choice for a shape whose narrow ends are its most vulnerable point. An east west setting, with the stone oriented sideways across the finger, is a distinctive modern alternative to the traditional lengthwise placement.
Explore Marquise Cut Pieces
Browse Nivara's marquise cut lab grown diamond rings, all IGI certified.
Frequently Asked Questions
How big is a 1 carat marquise diamond?
A one carat marquise measures roughly 11.2mm by 5.6mm at a standard 2 to 1 length to width ratio. Because the shape is long and narrow, it looks larger on the finger than a one carat round diamond. Your IGI certificate lists the exact measurements.
Does a marquise diamond look bigger than a round?
Yes. A marquise spreads its surface area across an elongated outline, so carat for carat it reads as one of the largest looking shapes, larger even than an oval or pear. It is the most size efficient cut for a given budget.
What length to width ratio is best for a marquise diamond?
Most buyers prefer a ratio near 2 to 1, usually between about 1.85 and 2.15. The certificate lists the exact ratio, and it is worth choosing the proportion that looks balanced to your eye.
Related guides: the complete guide to diamond shapes and the pear diamond size guide. To see the weight on a real setting, browse 1 carat lab grown diamond rings.
