Antwerp’s famous diamond district is often referred to as the Square Mile – several city blocks packed with 380 workshops serving about 1500 diamond companies. More than 80 per cent of the world’s rough diamonds and 50 per cent of cut diamonds pass through Belgium’s Diamantkwartier, making it the largest diamond centre – or bourse – in the world. And it’s not so easy to gain access to its inner sanctum.

“You need to be in the jewellery trade, and you need to know how to buy diamonds,” says gemologist Hamish Whiting. While the general public can wander through the bourse, meetings at the so-called trading offices are appointment-only, and you must be invited in the first place. “Not just anyone off the street can walk in.”

Hamish is from New Zealand but lives in Antwerp, so he’s uniquely placed to cherry-pick beautiful stones for Melbourne-based jeweller, Cushla Whiting, which Hamish founded with his sisters, Anna and Cushla. And the brand, which has won admirers for its expertise in both design and gemology, has recently begun to source rare antique diamonds for creative director Cushla to use in her designs.

While most diamonds in Australia are purchased by wholesalers from trading centres like the Antwerp bourse, then resold here, Hamish buys all Cushla Whiting diamonds directly. And it is at the Antwerp bourse that many families sell their family heirloom antique jewellery to diamond brokers.

“Most of the antique diamonds are not certified, so you have to grade the diamond yourself and value it and then negotiate on price with the trader,” he explains. “It's critical to see the stones in person … Genuine antique diamonds were cut by one cutter, by eye – not by computer-aided design.

“Each antique diamond has its own … unique character – the mark of the artist who cut it. However, just as there are huge differences in the quality of art, it's the same for antique diamonds. There is a huge variation in skill and artistry between different antique diamonds because there were very average cutters, and the ‘Picassos’ of the time.”

These diamonds were also cut “when lighting was inferior – mainly candlelight – and before [the official evaluations of the] Gemological Institute of America.”

The antique diamonds Hamish has acquired for Cushla Whiting were cut in the late 1800s and early 1900s by hand, a skill that has all but died out. These antique diamonds are exceedingly rare, especially as many of the older stones were recut into modern styles in the 1960s through to the 1990s.

While the exclusivity of these diamonds is fundamental to their luxury, they're also a more environmentally friendly choice compared to newly mined or lab-grown diamonds, both of which come with their own ethical and ecological shortcomings, from high energy use and carbon emissions in the case of lab-grown diamonds, to environmental degradation – deforestation, habitat destruction, pollution – and, in small-scale operations, labor issues in the case of mined diamonds, though safety and environmental practices by the now heavily-regulated large-scale miners have vastly improved in recent years. (Hamish stresses that all diamonds entering Australia must be Kimberley Process-certified, which means conflict-free, and that the lion's share of new mined diamonds are responsibly-sourced from major mining operations.)

Repurposed antique diamonds are a more sustainable option for those who are conscious of their carbon footprint. Sustainability and style have intersected with the rise of circular fashion, where vintage items are coveted for their uniqueness and reduced environmental impact (compared to new garments). Jewellery is experiencing the same trend.

Modern-cut diamonds account for around 99.9 per cent of the world's diamonds. They are cut in assembly lines with the aid of computers and scanners, rather than the artistic eye or skill of a single cutter.

There are also many companies around the world cutting modern diamonds into antique styles, then marketing them as antique diamonds.

“Unfortunately, there is currently no certification for genuine antiques to differentiate them from the replica antiques, which is why you really need to know what you’re doing and have experience looking at hundreds of genuine antiques to know the difference. It's like differentiating a genuine artwork or piece of furniture from an imposter,” Hamish explains.

Cushla Whiting predominantly sells the Old Mine cut and Old European cut antique diamond styles, which range in size from small side stones to centre stones that weigh between one and three carats. Antique diamonds are mostly warmer in hue than modern-cut diamonds, including some in a beautiful golden-hued champagne.

“The key difference for us … is having our gemologist on the ground at the bourse in Antwerp,” says Cushla. “Obviously not all antique diamonds are beautiful, in fact most are not, so having Hamish at the bourse handpicking the brightest and most beautiful diamonds is an invaluable offering. It is very difficult to buy from a distance, and seeing the diamond in person is critical with antiques.”

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