Marquise Lab Grown Diamonds

What is a marquise lab grown diamond?

A marquise lab grown diamond is a boat-shaped brilliant-cut stone, optically identical to a mined marquise diamond, produced in a controlled laboratory environment using either High Pressure High Temperature (HPHT) or Chemical Vapour Deposition (CVD) processes. The resulting crystal shares the same carbon-atom structure, refractive index, and hardness — 10 on the Mohs scale — as a naturally occurring diamond.

The marquise shape itself dates to eighteenth-century France, where a pointed oval cut was reportedly commissioned to mirror the curved lips of a royal courtier. Today the cut retains that theatrical outline: typically 1.85 to 2.15 in length-to-width ratio, though some cutters work narrower at 1.75 or wider at 2.25 for a more compressed or more elongated effect. The lab-grown route produces marquise diamonds to the same grading standards as mined stones — each certified by GIA, HRD or IGI — while frequently allowing a larger or higher-grade stone within a given budget.

How to choose a marquise lab grown diamond: cut, length-to-width ratio, and the bowtie effect

When selecting a marquise lab grown diamond, three technical factors matter most: the length-to-width ratio, the symmetry of the two pointed tips, and the presence and severity of the bowtie effect.

Length-to-width ratio governs how the stone reads on the finger. A ratio around 2.00:1 is considered classical — long enough to elongate the appearance of shorter fingers without appearing spindly. Ratios below 1.75:1 produce a wider, more oval-leaning silhouette; ratios above 2.15:1 create a very narrow, pronounced lance shape. Both tips should align precisely on the stone's longitudinal axis — even a slight deviation becomes visible once the diamond is set, particularly in a four- or six-prong solitaire.

The bowtie — a dark, bow-tie-shaped shadow across the centre facets — is present in virtually all marquise diamonds to some degree. Its visibility is a function of cutting angles and cannot be read from a grading report alone; reviewing actual imagery or video of each certified stone is advisable before committing. Lab grown production does not eliminate the bowtie, but careful cutter selection can minimise it.

What does a marquise lab grown diamond cost in the UK?

Marquise lab grown diamonds are generally priced significantly below their natural-diamond equivalents of the same carat weight, colour, and clarity — a gap that has widened as lab-grown production has scaled. The practical effect is that a 1.0ct or 1.5ct marquise lab grown diamond with D–F colour and VS clarity becomes accessible at a price point that would typically yield only a smaller or lower-graded natural stone.

For context, Bridebook's 2026 UK average engagement ring spend is £2,247. A marquise lab grown diamond at or around that budget will generally permit a stone comfortably above 1.0ct in a well-graded specification, though the final price is driven by the four Cs — carat, colour, clarity, and cut quality — as recorded on the GIA, HRD or IGI certificate. Buying loose allows precise control over every variable before committing to a setting; the stone can be purchased and inspected under the 30-day no-questions return window before any ring work begins.

Setting a marquise lab grown diamond: which styles suit the shape?

The marquise silhouette is one of the more setting-sensitive diamond shapes. Its two pointed tips are the most structurally vulnerable part of the stone — both to chipping and to light leakage — so the choice of prong configuration is consequential.

A six-prong setting with V-tips at each point is the most protective arrangement for a marquise lab grown diamond, directing metal coverage precisely over the fragile corners while leaving the belly of the stone open to light. Four-prong settings are feasible with careful prong placement but leave the tips more exposed. East–west orientations — where the stone is set horizontally across the finger rather than vertically along it — have grown in popularity for marquise lab grown diamonds specifically, as the broader silhouette creates a distinctive low-profile look that wears comfortably beneath gloves or adjacent rings. A bezel or half-bezel setting offers maximum tip protection for those who work with their hands. When the loose marquise lab grown diamond is set into one of our rings, it passes through CAD design, a silver or wax sample for review, casting, setting, polishing, and London Assay Office hallmarking before insured UK delivery.

Are marquise lab grown diamonds certified and fully returnable?

Every marquise lab grown diamond sold here carries a certificate from GIA, HRD or IGI — the three most widely recognised diamond grading laboratories — recording cut, carat weight, colour grade, clarity grade, and fluorescence. Lab grown stones are graded to exactly the same standards as natural diamonds under these systems, and the certificate makes no distinction in methodology.

All loose marquise lab grown diamonds are covered by a 30-day return window with no questions asked and no exclusions, and every order ships with complimentary insured UK delivery. If the stone is subsequently set into one of our rings, the ring carries a lifetime warranty and is eligible for free resizing for life, with hallmarking completed at the London Assay Office.