A Closer Look at

Argyle diamonds are revered all over the world for their captivating pink palette, and are as rare as they are beautiful. Less than 0.01% of diamonds in the world are coloured, and only 0.0001% of the 0.01% are pink. How they occur is romantically enigmatic; unlike most other coloured diamonds, their colour is caused not by trace elements in their chemical composition but by a lucky miracle of nature, a distortion within their atomic lattice caused by the pressure exerted on them during their formation.

Here, Madison Rose Whitman, Jewellery Specialist at Bonhams in New York, explains why Argyle Pink Diamonds are particularly precious and gives us a closer look at Lot 2 An Unmounted Fancy Vivid Purplish Pink Diamond and Lot 3 An Unmounted Fancy Intense Pink Diamond which are being offered in New York Jewels Online. Bidding opens on 1 April.

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(Pictured left) Lot 3. An Unmounted Fancy Intense Pink Diamond, Estimate $10,000 - $15,000. (Pictured right) Lot 2. An Unmounted Fancy Vivid Purplish Pink Diamond, Estimate $20,000 - $30,000.

Argyle Pink Diamonds

Argyle diamonds originate from the Argyle Diamond Mine in Western Australia. During its 37 years of operation, the mine became the world’s fourth biggest diamond producer by volume, generating over 865 million carats of rough diamonds. Overall, its output is of relatively low quality: only 5% of Argyle diamonds are gem quality, compared to a global average of 20%. However, that 5% includes some of the most extraordinary diamonds in the world.

The Argyle name is synonymous with rare pink diamonds. Although this colour accounts for less than 0.1% of its output, it was the only mine to consistently produce them, and, at its peak, it was responsible for over 90% of the world’s pink diamonds. In 2012, the mine unearthed Australia’s largest pink diamond, The Argyle Jubilee Diamond. Weighing 12.76 carats when it was found, the diamond was cut to 8.01 carats and donated to the Melbourne Museum, where it is on permanent display.

Origins

Throughout millennia of diamond mining, pink diamonds have been unearthed only occasionally, historically in India and later in Brazil, Indonesia and South Africa. The best specimens have been kept as treasures in the collections of royalty, rulers and museums, sought after and celebrated for their elusive beauty. Traditionally considered a gemmological curiosity, the last 50 years have seen a great shift in perception.

It was in the late 19^th-century that diamonds were first discovered in the remote East Kimberly region of Western Australia. Gold prospectors stumbled across ‘alluvial-deposited’ diamonds, so called because they had been moved from their primary source. For decades, only small quantities of these diamonds were found until a mission was launched to find the deposit in 1969. Ten years later, British geologist Maureen Muggeridge finally traced the source of the diamonds, and the ‘Argyle’ pipe was christened.

Mining commenced in 1983, and by 1985, Argyle was fully operational as an open pit mine. The small but regular supply from the mine, alongside informative marketing campaigns, piqued industry and public interest in pink diamonds and the rarity of coloured diamonds. In 2005, operations moved underground to facilitate access to the diamonds, but by 2020, the mine was no longer economically viable and operations ceased. Following the closure of the mine, the operator Rio Tinto has embarked on a four-year plan to rehabilitate the site.

Maureen Muggeridge by Megan Lewis

Lot 128. An Important Fancy Pink Diamond and Diamond Ring, By Meister, Circa 1968. Sold for £838,750 inc. premium.

Lot 128. An Important Fancy Pink Diamond and Diamond Ring, By Meister, Circa 1968. Sold for £838,750 inc. premium

Composition

The special composition of Argyle diamonds is thanks to its unusual geological origins. While most diamond mines are located on kimberlite pipes (made of igneous rock), the Argyle pipe is a volcanic pipe formed by a gaseous explosion. The diamonds in this area were formed approximately 1.58 billion years ago, nearly 100 miles below the earth’s surface, until the volcano brought them to the surface around 1.1 to 1.2 billion years ago.

Argyle diamonds appear in a range of colours. The vast majority are brown (known as “champagne”, “chocolate” and “cognac”), and less than 1% are fancy colour: pink, red, violet blue or green. It is thought that the signature pink colour of Argyle diamonds is due to extreme pressure during their creation, which caused structural defects in the crystal lattice. Such defects serve to alter the reflection of light as it passes through the diamond, creating the sought-after pink hues.

Highly Coveted

Even at the height of production in the 1990s, the Argyle Diamond Mine could not satiate the global demand for pink diamonds. Now that Argyle’s operations have ceased, that demand has only increased: we witnessed a 30% growth in the price of pinks following the mine closure in 2020. While there are other producers of pink diamonds around the world - from Angola to Brazil, Canada to Russia - none can compete with Argyle’s colour palette, quality or consistency.

The strong demand for natural pink diamonds speaks to the market’s consistent appreciation for the provenance, rarity and beauty of these stones. Unless the unlikely event occurs that another plentiful source is discovered, we expect the trend of record-breaking pink prices to continue indefinitely.

We are delighted to present two incredible Argyle diamonds in New York Jewels Online. With their vivid and intense colour saturations, these diamonds are an exemplar of the Argyle mine, and spectacular representations of a moment in gemmological history.

Register now to bid in the New York Jewels Online auction. For more information, contact madisonrose.whitman@bonhams.com.

Lot 139. A Fine Fancy Pink Diamond. Sold for £2,228,750 inc. premium.