The Ellendale Diamond Field is a cluster of 48 lamproite pipes stretching across 1,500 square kilometres of the Lennard Shelf, south of the Kimberley Block. These volcanic intrusions punched through the earth during the Miocene, between 22 and 19 million years ago. Over a wider 7,500-square-kilometre area, more than 100 lamproite intrusions have been mapped. Forty-five of the Ellendale pipes are volcanic crater deposits; three are classified as sills. The lamproites are either leucite-rich or olivine-rich, and 60 percent of them contain diamonds. What made Ellendale unusual among diamond sources was not the volume of stones -- grades ran low, between 5 and 14 carats per hundred tonnes -- but their quality. Between 75 and 90 percent of diamonds recovered were gem quality, including colourless, fancy yellow, green, and brown stones.

Ellendale became the largest single source of fancy yellow diamonds in the world. Where most diamond mines produce less than one percent fancy yellows, Ellendale's output ran at approximately 12 percent. In 2009, Tiffany & Co. signed an exclusive life-of-mine offtake contract through its subsidiary Laurelton Diamonds with the Kimberley Diamond Company for every fancy yellow diamond meeting what Tiffany called TQ -- Tiffany Quality -- standards. The partnership launched Tiffany's Yellow Diamond collection in Japan in April 2010, followed by a US debut later that year. For a few years, the remote Kimberley pipes were feeding some of the most recognisable jewellery showcases on Fifth Avenue. The arrangement made Ellendale a name in boardrooms from New York to Antwerp, even as the mine itself remained accessible only by dirt roads through country most diamond buyers would never see.

A routine blast at the E9 pit in June 2013 accidentally undermined the main access ramp -- the only way in and out of what was then the sole operational pit. For five months, the Kimberley Diamond Company survived on limited ore stockpiles while the ramp was repaired. By the time it was fixed, the wet season forced another postponement, cutting the company off from the yellow diamonds that generated 80 percent of its cash flow. Mining resumed in 2014 and produced some 120,000 carats, but rising costs from the damaged pit made operations increasingly uneconomic. In July 2015, the Kimberley Diamond Company entered administration and then liquidation. The site was declared abandoned that December. At the time of closure, Ellendale was producing an estimated 50 percent of the world's fancy yellow diamonds. Both the E4 and E9 pits flooded.

Here is where Ellendale becomes genuinely strange. Geologists have calculated how many diamonds should have eroded out of the lamproite pipes over millions of years and washed into alluvial deposits downstream. The number of carats actually found in alluvial beds falls far short of those calculations. The discrepancy is large enough to have earned a name: the Lost Alluvials of Ellendale. Somewhere beneath the Kimberley, trapped in buried river channels and ancient drainage systems, a substantial reserve of diamonds is calculated to remain undiscovered. The mystery deepened in 2017 when India Bore Diamond Holdings discovered diamonds in the L-Channel, a drainage system running south past several lamproite pipes and overlaying a much older, deeply buried freshwater aquifer. Bulk samples from the L-Channel produced high-quality fancy yellows consistent with E4 and E9 stones. In 2023, IBDH re-commenced mining operations targeting this deposit -- the first licensed mining at Ellendale since 2015.

Ellendale continues to produce surprises. Near the E12 pipe, alluvial beds yield diamonds with distinctly different morphology and colours from those found in the main Terrace 5 channel just 300 metres away -- including green diamonds. The E12 pipe itself tests as nearly barren, meaning the diamonds found near it almost certainly came from somewhere else, a source that has not been identified. In 2020, IBDH reported discovering diamonds from the L-Channel that fluoresced purple under long-wave ultraviolet light. While roughly 35 percent of natural diamonds show some fluorescence, purple fluorescence has been reported only rarely, and the mechanism that produces it remains poorly understood. For a field that was abandoned to floodwater and administrators less than a decade ago, Ellendale remains one of the most geologically provocative diamond deposits on Earth -- a place where the stones keep appearing in places they should not be, in colours no one expected.