Formal:
* Adiós, hermosa. (This is the most direct translation, but sounds a bit formal.)
* Hasta pronto, hermosa. (This means "See you soon, beautiful" and is more appropriate for a friend or someone you know well.)
Informal:
* Chao, hermosa. (This is a more casual and friendly goodbye.)
* Te quiero, hermosa. (This means "I love you, beautiful" and is more appropriate for someone you're close to.)
* Hasta luego, hermosa. (This means "See you later, beautiful.")
You can also add a compliment or a sweet sentiment to make it more personal, like:
* Adiós, hermosa. Que tengas un buen día. (Goodbye, beautiful. Have a good day.)
* Hasta luego, hermosa. Te veo pronto. (See you later, beautiful. I'll see you soon.)
The best option will depend on the situation and your relationship with the person you are saying goodbye to.