SOLVED. YA Fantasy. Royal families grouped by jewel types, and a talking dog. Cover: brunette with braid, green dress, lots of green. Title: include "Emerald Moon"? Spoilers ahead.

[Belinda]

I read this book between 1997 - 2003. The main character is someone who gets magically paired with a tutor against her will; they wear similar emerald rings I think which link them and allow them to continue to speak with each other.

SPOILERS
Her tutor is turned into a talking dog against his will, and we spend much of the book trying to get him back to his human shape while trying to save a princess/duchess/something from being killed or poisoned before a deadline which would make the crown move to the next jewel-based royal family.

[Belinda]

Oh my gosh. This group is amazing. I tried searching just "emerald" and found the title. It's