Colour, clarity, and carat: The ingredients of a high-quality diamond

While lab-grown diamonds are increasing in popularity, auctioneers warn that the prices of these ‘fall off a cliff’ when it comes to resale

Three-stone ring set in 18ct gold with a diamond weight of 3.14 ct (€15,000-€18,000) at John Weldon Auctioneers
Three-stone ring set in 18ct gold with a diamond weight of 3.14 ct (€15,000-€18,000) at John Weldon Auctioneers

It’s a family affair at John Weldon Auctioneers on Cow’s Lane, Temple Bar, Dublin. John, with his sister, Joan, runs the auction rooms, while their mother, Gail, who died recently, worked alongside her adult children when they first set up their business in 2001 in the old city lane then transformed into a trendy shopping street.

“We’re the greenest business on the street as everything is repurposed and reused,” says John.

John Weldon and his sister, Joan, at the John Weldon auction rooms on Cow's Lane, Temple Bar, Dublin
John Weldon and his sister, Joan, at the John Weldon auction rooms on Cow's Lane, Temple Bar, Dublin

The Weldons have been in the antique business for three generations as John and Joan’s grandfather, JW Weldon, set up the original family business on Clarendon Street, Dublin 2 in the 1940s. Their father, Jimmy, and brother, Garrett, still run that antique shop while another brother, Matthew Weldon, runs Courtville Antiques in Powerscourt Townhouse Centre.

But John Weldon Auctioneers is the only one in the family that runs monthly auctions. Its next jewellery and silverware auction – on June 11th at 2pm – has more than 320 lots, most of which is jewellery (watches, rings, pendants). It is being sold on behalf of solicitors, executors, and couples splitting up, moving house or simply cashing in their investments.

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Weldon highlights two particular diamond rings – a three-stone ring set in 18ct gold with a diamond weight of 3.14ct (€15,000-€18,000), and a three-stone ring set in 18ct gold with diamond weight of 3.20ct (€4,000-€6,000) – in next week’s auction to give us a crash course in working out what marks out high quality in a diamond ring.

“The clarity or colour of the diamonds is what counts. You’re looking for a diamond that is the colour of water; the more colourless it is, the more valuable it is,” he explains. Another key aspect of higher-quality diamonds is that they won’t have internal carbon markings on the stone. Weight counts too, and the more carats the better – each carat (ct) weighs 200 micrograms, which is one fifth of a gram.

Weldon Auctioneers sells natural and lab-grown diamonds in its auctions. “We test them to see if they are natural, and there is a marked difference in price. Natural diamonds hold their value, while lab-grown diamonds fall off a cliff when they are sold at auction,” explains John.

A diamond halo cluster engagement ring (€2,000-€3,000)
A diamond halo cluster engagement ring (€2,000-€3,000)

By way of example, he estimates that a one-carat natural diamond will sell at auction for €4,000-€5,000, having been purchased new for €10,000-€12,000. Meanwhile, an equivalent lab-grown diamond will sell at auction for €500-€800 and would have cost about €3,000 new.

Tuesday’s auction at Weldon Auctioneers in Cow’s Lane will also have a range of watches and diamond pendants for sale, many of which have the original receipt showing the price paid when first bought. And there is a diamond halo cluster engagement ring (€2,000-€3,000) with a copy of the valuation which states the total diamond weight is 1.64ct and was valued at €9,400 in October 2021. One can’t help but wonder why this pandemic purchase ended up in an auction.

A selection of items on sale at the jewellery, silver and collectibles auction at Matthews Auction Rooms in Kells, Co Meath on Sunday
A selection of items on sale at the jewellery, silver and collectibles auction at Matthews Auction Rooms in Kells, Co Meath on Sunday

Meanwhile, Matthews Auction Rooms in Kells, Co Meath, will host a jewellery, silver and collectables auction tomorrow (Sunday June 9th) at 5.30pm. With 730 lots from a variety of clients, Damien Matthews suggests that “there will be great value for discerning buyers”.

18 carat yellow gold asscher cut diamond cufflinks (€2,000-€3,000) at Matthews auction
18 carat yellow gold asscher cut diamond cufflinks (€2,000-€3,000) at Matthews auction

He chooses a pair of 18ct yellow gold Asscher cut diamond cufflinks (€2,000-€3,000) as his favourite item from the auction. Asscher cut diamonds are named after Joseph Asscher, who, in 1902, first made these particular cuts which give many faces or sides to the stone. They became popular in the Art Deco period and now have a certain antique charm.

And in the spirit of reuse and recycling, it’s interesting to note that the Matthews auction includes a pair of Versace sunglasses with their original case (€40-€70); three pairs of Prada sunglasses, each with their original case (also at €40-€70 each); and two pairs of Tom Ford sunglasses, with original case (also at €40-€70 a pair).

A diamond- and ruby-set fox motif brooch (€1,200-€1,800) at Matthews auction
A diamond- and ruby-set fox motif brooch (€1,200-€1,800) at Matthews auction

There are plenty of other curiosities too, including the cutest diamond- and ruby-set fox motif brooch (€1,200-€1,800), and bundles of costume jewellery that bargain hunters will enjoy browsing through.

The National Antiques Fair at Limerick Racecourse
The National Antiques Fair at Limerick Racecourse

And finally, there will be at least 80 dealers selling their wares at the National Antiques Fair at Limerick Racecourse next Saturday and Sunday (June 15th and 16th). Run by Robin O’Donnell of Hibernian Antique Fairs, it’s the third of five antique fairs at this venue this year. It’s the perfect place to forage for vintage jewellery, Irish silverware, china and porcelain – not to mention an antique piece of furniture which will add a little character to a modern or period home – while shopping sustainably at the same time.

jwa.ie; matthewsauctionrooms.com; antiquesandartireland.com

What did it sell for?

Walter Frederick Osborne’s Early Morning in the Market, Quimperlé

Auction price: €120,000-€160,000

Hammer price: €110,000

Auction house: Adam’s

Flora H Mitchell’s ink and watercolour drawings of the Campanile, Trinity College Dublin

Auction price: €2,000-€3,000

Hammer price: €2,500

Auction house: Whyte’s

A bronze crab sculpture

Auction price: €8,000-€12,000

Hammer price: €10,000

Auction house: Victor Mee

Sylvia Thompson

Sylvia Thompson

Sylvia Thompson, a contributor to The Irish Times, writes about health, heritage and the environment