Kate wore these earrings a few times in 2007.
Here they are at the “Time to Reflect” book launch.
The closeup is from My Small Obsessions.
They are a single piece of black onyx cut into an octagonal shape. The piece is set in
gold (I suspect it’s gold plated). silver or silver tone (I think the brightness on my screen is off. It looked gold to me at first). The drop is attached to a small black onyx stud affixed to a post. The connecting link and the post are also goldtone.
She wore them to nightclubs in 2007.
If anyone can find similar-looking earrings for sale at any retailer, contact me and I will update the post.