Emeritus Professor Claus Diessel is acknowledged internationally as one of the world's greatest geologists and petrographers and is an expert in the application of coal petrology to commercial utilisation of coal and coke. His finding that coal constituent Inertinite, did contribute to coal quality against previous beliefs heldby overseas buyers, greatly increased industry's ability to successfully market coal internationally at high volumes and prices.

His further basic research on coal deposition systems and, more recently, on the possible relationship to oil deposits, has provided continuing benefits to industry.

The economic contributions of his work to industry and Australia are measured in millions of dollars.