Picture examples for the question.
Round: http://www.wallpaperbase.com/wallpapers/celebs/aishwaryarai/aishwarya_rai_2.jpg
Medium-round: http://www.celebrityweasel.com/wp-content/uploads/2006/10/katie_holmes_tom_cruise_weddings_celebrity_weddings.jpg
Medium-thin: http://i.thisislondon.co.uk/i/pix/2007/09/keira2PA_243x365.jpg
Thin: http://www.bartcop.com/jlh-01.jpg
Round: http://www.wallpaperbase.com/wallpapers/celebs/aishwaryarai/aishwarya_rai_2.jpg
Medium-round: http://www.celebrityweasel.com/wp-content/uploads/2006/10/katie_holmes_tom_cruise_weddings_celebrity_weddings.jpg
Medium-thin: http://i.thisislondon.co.uk/i/pix/2007/09/keira2PA_243x365.jpg
Thin: http://www.bartcop.com/jlh-01.jpg