Evening Queen Letizia repeated her earring from her arrival to Mexico. I recognized these easily, they are by Tous and made of emeralds, rubies, and moonstones. She seems to be wearing them a lot lately.
The new earrings are also by Tous and are made of rubies and emeralds. I couldn't find them on their website but I did find this picture on Tous's Pinterest.
According to Queen Letizia's Style the next pair of earrings are by Folli Follie. They are rose gold plated with crystals and she has worn them at least once before during the State Visit to France with the same outfit. Folli Follie - Elements Earrings
I guess the only mystery earrings left are the beautiful diamond earrings she wore to the banquet and the ruby earrings from the beginning of Day 3 that she has worn many times before.