On January 31, 2018, Kate wore these earrings in Sweden.

They’re quite large and somewhat casual (in design) for Kate, especially given that she’s taken to wearing more royal jewels in recent years. The earrings consist of a large teardrop pendant made of 14ct white gold and set with a single, uniform row of white diamonds. They are affixed to white gold leverbacks, the front facing sides lined with white diamonds.
Here they are on Kate:
They cost £4,900 or $6,545 USD.