Their presence in the diamond tells a story of a journey, indicating the stone formed at depth before making its way back up to the crust.
The ringwoodite in particular had features suggesting it is hydrous in nature – a mineral that forms in the presence of water.
These clues suggest that the environment in which the diamond formed was pretty danged wet.
"Even though a local H2O enrichment was suggested for the mantle transition zone based on the previous ringwoodite finding, the ringwoodite with hydrous phases, reported here – representative of a hydrous peridotitic environment at the transition zone boundary – indicates a more broadly hydrated transition zone down to and cross the 660-kilometer discontinuity.".