Don't know what to make of this, but the greatest popular singers of the 20 century (of the countries I know), were also extremely beautiful...
Billie Holiday (USA)
http://www.pbs.org/wnet/americanmasters/database/holiday_b.html
Edit Piaf (France)
http://en.wikipedia.org/wiki/Edith_Piaf
Amalia Rodrigues (Portugal)
http://en.wikipedia.org/wiki/Am%C3%A1lia_Rodrigues
Maria Tanase (Romania)
http://www.roembus.org/english/journal/invitatii/invitatie%20Teodora%20Enache.pdf