The 6mm diameter pearl was unearthed during archaeological excavations in 2011 in a “shell midden” – a site where oyster shells have accumulated over time – located on the Kimberley coast of Western Australia.
Kat Szabó, associate professor at the University of Wollongong (UOW), one of the universities involved in the Kimberly coast archaeology project, told Jeweller that it took four years to verify the gem’s age because the team had to develop and gain approval for a special series of tests.
“Pearls have not been recovered before from ancient sites in Australia. Since the find is unique, analysis could not damage or take samples from any portion of the pearl, so researchers from UOW developed a range of non-destructive analyses to gather more information,” she said.
Using micro-computer tomography and radiocarbon analysis of the surrounding shell midden material, researchers were able to determine that the gem was about 2,000 years old and that it had grown naturally inside an oyster for more than a decade before the mollusc was harvested.
The fact that the pearl formed naturally is even more significant because of its near spherical shape – said to be rare in natural pearls – and that it had been found in a region well-known for cultured pearl production.
Szabó explained that although the pearl itself did not appear to hold cultural significance for the indigenous people living in the area during that time, the pearl oyster shells that produced pearls did. She said one of the most distinctive indigenous cultural artefacts from the Kimberley coast area was a pendant made from pearl oyster shell referred to as ‘riji’, adding that the shells had also been used to perform rainmaking ceremonies.
Following its discovery, Szabó received numerous enquiries as to whether the pearl was available for sale. However, given it had been classified as a cultural object, she said it couldn’t be sold, and that regardless, it would be difficult to put a monetary value on such an “irreplaceable” heritage item.
The pearl will tour Australia as part of the Lustre Exhibition, which will start on 20 June at the Western Australian Maritime Museum (WAMM), before becoming part of the WAMM’s permanent collection.