These gowns are both from the Kyoto Costume Institute and date from
c.1911.
The dress on the left is by Jeanne Lanvin, and is green silk chiffon and
tulle lace, floral embroidery, and rose flower ornament.
As for the dress on this right, much less is known of its origin; I can
only say that it uses beige silk tulle and pink silk chiffon, floral embroidery
of beads and fake pearls, and gold cord embroidery on skirt.
The KCI also says this about the dresses:
"These dresses have a high waist silhouette, which is
representative of the early 1910s. This silhouette spread among designers,
starting from Paul Poiret's "Lola Montez" dress in 1906. Distinctive,
vivid colors on delicate materials such as silk chiffon were achieved in this
period by use of synthetic dyes. These hues can be also found in the highly
exotic, strong colors used in the costume of the Ballets Russes, which first
performed in Paris in 1909. Those colors immediately influenced fashion
circles, and in the early 1910s, the streets were filled with vivid colors like
those seen in these dresses."
Despite any fashion for brightly coloured dyes, almost all the images I
see of outfits from the Edwardian period are (for obvious reasons) severely
monochrome. It's amazing to see the real colours- and so vivid after a hundred
years! The curators of these gowns have done a bang-up job.