A 24.31 ct D Internally Flawless Diamond Ring and the £1.87 Million Result
A single step-cut diamond at the very top of the colour and clarity scales, and what those grades actually mean.
On 5 December 2018, a ring set with a single step-cut diamond of 24.31 ct sold at Bonhams, New Bond Street, London, for £1,868,750 including buyer's premium. GIA graded the stone D colour and Internally Flawless, and classified it as Type IIa.
The result
On 5 December 2018, at its Fine Jewellery sale in New Bond Street, London, Bonhams sold lot 133, a ring set with a single step-cut diamond of 24.31 ct, for £1,868,750 including buyer's premium.
What it was
The diamond sits in a four-claw setting. GIA graded it D colour and Internally Flawless, and a separate GIA letter, dated June 2018, classified it as Type IIa.
What the grades mean
D colour is the top of GIA's colour scale for white diamonds: no detectable body colour.
Internally Flawless means a trained grader finds no inclusions under 10x magnification, only possible minor surface marks. It sits just below Flawless on the GIA clarity scale.
Type IIa diamonds contain almost no nitrogen. They are a small minority of all diamonds and are prized for their exceptional transparency.
Why the cut matters
A step cut, such as an emerald or Asscher cut, has long, flat facets that act like a window into the stone. Inclusions and any tint show clearly, so cutters reserve the style for very clean, very white diamonds. Pairing a step cut with an Internally Flawless grade is a sign of confidence in the material.
For buyers of everyday diamonds
The same ideas apply at any size. Colour, clarity and cut matter most when they are confirmed by a report from a recognised laboratory, and a step cut rewards a clean stone more than a brilliant cut does. When you buy or sell, ask what report a diamond has, who issued it and whether it matches the stone in front of you.
If you would like a diamond of your own identified and valued, send us photographs through our valuation form.
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About Mozeris Fine Antiques
Mozeris Fine Antiques is a dealer in fine jewellery, watches and silver, with offices in Mayfair, London, and Braintree, Essex. We buy and sell, and offer free valuations. Visits are by appointment.
Price as published by Bonhams, including buyer's premium. Mozeris Fine Antiques is not connected with Bonhams. No auction-house images are used; the photograph shows a piece from our own stock.
