ROCK OF AGES: April has always been an important month for diamonds, and the Natural Diamond Council is doubling down on tradition with the launch of World Diamond Day on April 8.
The organization said it wants to highlight the beauty and staying power of mined rocks, and is inviting people to share “meaningful moments” in person and on social media. It even has downloadable assets and logos on its site to help people tell their personal and professional stories.
World Diamond Day is taking place at a challenging time for mined diamonds. The rocks’ index value fell 11.5 percent between March 2025 and March 2026, and has not recorded positive monthly growth since June of last year, according to a study by 77 Diamonds, an online diamond jewelry retailer with showrooms in the U.K. and Europe.
Natural stones have come under pressure from their lab-grown cousins, which have also seen their value fall over the past year due to mass distribution, and from the rising price of precious metals which has made fine jewelry more expensive.
According to 77 Diamonds, larger, high-quality natural stones, particularly those with exceptional cut, clarity and provenance, have remained more resilient than their smaller, less glamorous cousins.
De Beers and Sotheby’s will put that observation to the test when The Jwaneng 28.88 hits the auction block later this month as part of Sotheby’s Luxury Sales in Hong Kong.
The Jwaneng 28.88.
The Jwaneng is an internally flawless, D-color, 28.88-carat diamond unearthed from the eponymous mine in Botswana. Its name means “a place of small stones” in the Setswana language, and it carries an estimate of $2.2 million to $2.8 million.
Millions of years old, it was carried toward the surface by volcanic eruptions beneath what is now the Kalahari Desert in southern Africa.
It was cut from a 114.83-carat rough diamond, and underwent months of study and planning by De Beers’ specialists.
The result is a flawless round brilliant classified as “Type IIa,” which is the rarest and most chemically pure category of natural diamond, representing fewer than 2 percent of all diamonds discovered, according to Sotheby’s.
“The Jwaneng 28.88 is a vanishingly rare feat of nature combined with a masterclass in diamond cutting and polishing,” said Quig Bruning, Sotheby’s head of jewels Americas and EMEA.
Sotheby’s Live High Jewelry Sale will take place on April 23, and the Jwaneng 28.88 will be auctioned alongside additional De Beers diamonds from the same mine.
