Rose's Breakfast Dress consists of two pieces: a yellow gold strapless underdress and a white lace overdress with yellow flower trim. There are some fantastic sites online that have already researched the gowns from Titanic - check out the links included below.

Underdress - The strapless underdress is very fitted at the bust, then flares freely from the waist into an A-line shape, creating very pretty folds in the skirt. There is a lace inset (V) in the front of the bodice. The underdress is a yellow gold in color, probably made from silk charmeuse.

Overdress - The trained lace overdress has a peaked empire waist and short 'hankerchief' sleeves. The lace is very delicate, almost like a net. The neckline and sleeves are trimmed further with approx. 2" wide lace. There is also narrow green and yellow flower trim around the neckline, which ties in the front of the overdress as a false closure. The overdress most likely closes with hooks-and-eyes in reality. Due to the cut of the sleeves, the hem hangs a little longer in back than front, and at the corner of each 'point' is a crystal drop bead (4 total).

Linkage:
Maggie's Titanic Costume Research
Jenny's Breakfast Gown Observations
J. Peterman Costume Collection - awesome reproductions
Sense & Sensibility's Titanic Project