A lab-grown marquise diamond is a long, boat-shaped stone with pointed ends. It has the largest face-up area of any classic shape for its weight, so a marquise looks bigger on the finger than a round of the same carat, and it makes fingers look longer and slimmer.
This guide explains how big a marquise looks at each carat weight, how to judge the length-to-width ratio and the bow-tie, which settings protect the points, and what real marquise stones cost in our catalogue. If you are new to lab-grown stones, start with what a lab-grown diamond is.
What is a marquise-cut diamond?
The marquise is a brilliant cut, so it has facets designed for sparkle, like a round or oval. It is long and narrow with two pointed tips. Because so much of its weight sits in the visible top of the stone and not in its depth, it spreads wider than most shapes.
A lab-grown marquise has the same chemistry, hardness and optical properties as a mined one. Every stone we sell comes with an IGI or GIA report, which records its carat weight, colour, clarity and exact measurements.
How big is a lab-grown marquise diamond?
The table gives approximate face-up sizes for well-proportioned marquise stones with a ratio of about 2:1. Individual stones vary, and the measurements on the grading report are the ones to trust.
| Carat weight | Approximate marquise size | Approximate round of the same weight |
|---|---|---|
| 0.50 ct | about 10 × 5 mm | about 5.1 mm |
| 1.00 ct | about 12 × 6 mm | about 6.4 mm |
| 1.50 ct | about 14 × 7 mm | about 7.3 mm |
| 2.00 ct | about 15 × 7.5 mm | about 8.1 mm |
A 1-carat marquise is roughly twice as long as a 1-carat round is wide. That is why many people choose a marquise when they want a stone that looks generous without paying for extra weight.
How to choose a good marquise
Length-to-width ratio
Most buyers like a ratio between about 1.85 and 2.10. Lower ratios look fuller and softer, and higher ratios look slimmer and more dramatic. You can work out the ratio by dividing the length by the width on the report.
The bow-tie
Like ovals and pears, many marquise stones show a darker band across the middle, called a bow-tie. A faint bow-tie is normal and adds contrast. A heavy, very dark one reduces sparkle. Check the photos or video of each stone before you choose.
Symmetry
The two halves and the two points should line up. Small differences are hard to see once the stone is set, but a clearly lopsided marquise is noticeable on the hand.
Colour and clarity
Colour can gather slightly in the points of a marquise, so many buyers choose G or better for white gold or platinum. Inclusions near the tips are worth avoiding, because the points are the most exposed part of the stone. Read more in our guide to near-colorless diamond colour.
What does a lab-grown marquise diamond cost?
These are real listings from our catalogue on 26 October 2026. Prices change as stones sell, so each listing shows its current price.
| Stone | Price on 26 October 2026 |
|---|---|
| 1.2 ct marquise, D colour, VS1 | €550 |
| 1.5 ct marquise, E colour, SI1 | €740 |
| 1.5 ct marquise, D colour, VVS2 | €810 |
| 2 ct marquise, H colour, VS1 | €890 |
| 2 ct marquise, F colour, VVS2 | €900 |
A budget of €500 to €1,000 covers marquise stones from around 1.2 carats to 2 carats with high colour and clarity grades. Browse all lab-grown marquise diamonds to compare current stones.
Best settings for a marquise diamond
Protect the points
The tips are the most delicate part of a marquise. V-shaped prongs or claws over each point protect them from knocks and are the most common choice.
Solitaire, east-west or with side stones
A classic north-south solitaire makes the most of the stone's length. An east-west setting turns it sideways for a modern look. Small side stones or a pavé band add sparkle without competing with the centre. You can try combinations in our ring customizer, with settings from about €490.
Is a marquise right for you?
Choose a marquise if you want maximum size for the carat weight, a vintage feel and a shape that flatters the hand. If you prefer something softer, an oval offers a similar elongated look with rounded ends. Our oval lab-grown diamond guide compares the two.
Every stone comes with free EU shipping, no import duties and a 30-day return, so you can see it in person before you decide.
Frequently asked questions
Does a marquise diamond look bigger than a round?
Yes. Because a marquise is long and shallow, it has more visible surface area than a round of the same weight. A 1-carat marquise is about 12 mm long, while a 1-carat round is about 6.4 mm across.
Are marquise diamonds fragile?
The diamond itself is just as hard as any other shape, but the pointed tips can chip if they are hit hard. A setting with V-prongs over the points protects them.
What is the best ratio for a marquise diamond?
Most people prefer a ratio between about 1.85 and 2.10. It is a matter of taste: lower looks fuller and higher looks slimmer.
How much is a 1.5-carat lab-grown marquise?
On 26 October 2026, 1.5-carat marquise stones in our catalogue included an E SI1 at €740 and a D VVS2 at €810. Each listing shows its current price.
Are lab-grown marquise diamonds certified?
Yes. Every stone we sell has an IGI or GIA grading report. See our IGI vs GIA guide for how the two labs compare.
How we wrote this guide: written by the VAALBERG team. Prices are individual listings from our own catalogue on the date shown; sizes are approximate and the report measurements are authoritative.
