thorough-bred

hi!
I've found in the dictionary that thorough-bred means "pura sangre"but what would you say if you apply this adjective to a person??
It appears in the following sentence " her voice was as bright and lively as it was thorough-bred" (it's talking about a posh and perky girl)
I have translated it as " como si fuese de la realeza"
What do you think?

Su voz era vivaz y alegre aristocrática.

Ahhh! ok I hadn't seen the As... As. Now it makes more sense. Thank you Filis Cañí