With dark eyes and eyelashes she would have been a beauty. 
( ( With ( dark ( ( eyes and ) eyelashes ) ) ) ( she ( ( would ( have ( been ( a beauty ) ) ) ) . ) ) )
(ROOT (S (PP (IN With) (NP (JJ dark) (NNS eyes) (CC and) (NNS eyelashes))) (NP (PRP she)) (VP (MD would) (VP (VB have) (VP (VBN been) (NP (DT a) (NN beauty))))) (. .)))
She would have been the most beautiful with brown eyes.
( She ( ( would ( have ( been ( ( the ( most beautiful ) ) ( with ( brown eyes ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP She)) (VP (MD would) (VP (VB have) (VP (VBN been) (NP (NP (DT the) (ADJP (RBS most) (JJ beautiful))) (PP (IN with) (NP (JJ brown) (NNS eyes))))))) (. .)))