Radiant Lab Grown Diamonds

What is a radiant lab grown diamond?

A radiant lab grown diamond is a stone produced in a controlled laboratory environment — using either High Pressure High Temperature (HPHT) or Chemical Vapour Deposition (CVD) — then cut into the radiant shape, which features cropped corners, a rectangular or square outline, and between 70 and 74 facets arranged in a distinctive criss-cross pattern beneath the table. The resulting stone is chemically, physically, and optically identical to a mined radiant diamond; the difference lies entirely in origin. Because lab grown production removes the constraints of geological scarcity, radiant lab grown diamonds are typically available at a lower cost per carat than their naturally mined counterparts, allowing for a notably larger stone or higher grade within the same budget. The radiant cut was developed in 1977 by Henry Grossbard specifically to bring brilliant-cut light performance to a rectangular outline — a combination that had previously eluded step cuts such as the emerald.

How does the radiant cut compare with other diamond shapes?

The radiant cut occupies a distinct position among diamond shapes: it delivers more light dispersion than the emerald or Asscher cut, yet carries a less conventional outline than the round brilliant. Its criss-cross facet structure generates broad flashes of white light and scattered colour, rather than the concentric hall-of-mirrors reflection associated with step cuts. In a radiant lab grown diamond, these optical qualities are undiminished by origin — the facets respond to light in exactly the same way as in a mined stone. Length-to-width ratio shapes the character significantly: a ratio near 1.00–1.05 produces a square radiant, while 1.20–1.35 gives a more elongated rectangle. The elongated radiant creates a visual stretching effect on the finger that can make the stone appear larger face-up relative to its actual carat weight, a particularly useful consideration when choosing a lab grown stone where higher carat weight is more accessible on a given budget. The cut also conceals inclusions well due to its dense facet pattern, making VS2 and even SI1 clarity grades appear clean to the unaided eye in many cases.

What do radiant lab grown diamonds cost in the UK?

Radiant lab grown diamonds are priced according to the same four-variable framework as any diamond — carat weight, cut quality, colour grade, and clarity — but the starting point per carat is substantially lower than for natural radiants of equivalent specification. Bridebook's 2026 UK average engagement ring spend of £2,247 gives a useful reference point: a radiant lab grown diamond at that budget can realistically reach 1.0ct or beyond in the F–H colour range with a VS or SI clarity grade, whereas a natural radiant of comparable specification would typically require a considerably higher outlay. Price differences between colour grades (D through J) and clarity grades (FL through SI2) remain meaningful within the lab grown category, so it is worth deciding which variable matters most before filtering. All radiant lab grown diamonds in our collection carry GIA, HRD or IGI certification, so the grade printed on the report is independently verified rather than dealer-assigned.

How are radiant lab grown diamonds certified?

Every radiant lab grown diamond available through President Jewellers is certified by one of three independent grading laboratories: GIA (Gemological Institute of America), HRD Antwerp, or IGI (International Gemological Institute). Each certificate documents the stone's carat weight, colour grade, clarity grade, cut proportions, and origin as laboratory-grown. This independent verification means the grade on the certificate is assigned by a grader with no commercial interest in the stone's valuation. When comparing radiant lab grown diamonds, the certifying laboratory should be noted alongside the grade — GIA and HRD reports are widely regarded as applying strict grading standards, while IGI has invested substantially in standardising its lab-grown grading protocols in recent years. All three laboratories are fully accepted by insurers, which matters when arranging cover for the finished ring.

Setting a radiant lab grown diamond into a ring

The radiant cut's cropped corners make it more resistant to chipping at the tips than pointed shapes such as the marquise or pear, yet the corners still benefit from being protected by claw tips or a bezel edge in the finished setting. Four-claw settings allow maximum light to enter and leave the facets from all angles; a six-claw arrangement offers greater security for larger stones. Channel-set or pavé side stones pair particularly well with the radiant cut's rectangular outline, echoing its geometry without competing with the centre stone's light performance. When a radiant lab grown diamond is selected and set into one of our rings, the piece is crafted at our Hatton Garden workshop through a process of CAD design and silver or wax sample review before casting — a lead time of 7–14 working days from order confirmation, with every finished ring hallmarked at the London Assay Office. Loose radiant lab grown diamonds may be returned within 30 days, no questions asked, with no exclusions.