Sean Fallon of Fashionably Geek refers to these hairstyles "unicorn braids." That's a great name! Shelley Gregory of Square Salon in Las Vegas is responsible for giving these women enchanted braids look like they emerged from fairy tales.
Square Salon refers to this one as "real life mermaid hair." That's a very apt description! The braid looks like a mermaid's tail. It's like the female equivalent of merman hair.