Kate wore these statement earrings back in 2009 to the film premiere of “Tenacity on the Tasman”.
Here is the closeup:
They appear to be a gold hoop connected to a chain (or solid gold bar) which is attached to a smaller gold hoop connected to a hook. There are a series of thin gold bars dangling from the second, larger hoop. They look like spikes when she moves her head. It looks like the outer bars are smaller, and increase in length from the outside to the inside.
I believe these are fashion/costume jewelry earrings.
She also wore these earrings during a night out with William the same year.