The 30.24-carat Ana Maria Pearl – named for one of its alleged owners, Ana Maria de Sevilla y Villanueva, Marchioness of Camarasa – was thought to have been recovered from the Americas in the 1500s.
The natural saltwater baroque pearl was examined by the Swiss Gemmological Institute SSEF in Basel and the Ion Beam Physics Laboratory at ETH Zürich university, which established it formed sometime between 1500 and 1650.
Radiocarbon dating was developed in the 1940s and is frequently used in archaeology and palaeontology. It measures the amount of carbon-14 isotope in a sample to determine its age, as carbon-14 degrades at a stable rate.
But there’s a catch: it can only be used to date organic objects, making it useless for things like metal. As pearls come from a living animal, they are able to be radiocarbon dated.
Dr Michael Krzemnicki, SSEF director, said, “We are in the process of further developing radiocarbon analysis and other scientific techniques to verify the historic provenance of antique jewellery and iconic natural pearls.”
The Ana Maria Pearl will be auctioned by Christie’s Geneva this week.