Jumeau was a French company, founded by Louis-Desire Belton and Pierre-François Jumeau in the Maison Jumeau of Montreuil-sous-Bois, near Paris, in the early 1840s. The company designed and manufactured high quality bisque dolls.
While Belton did not remain with the company for long, under Jumeau's leadership (and later, under the leadership of his son, Emile), the company soon gained a reputation for dolls with beautiful faces and "exquisite" clothing which replicated the popular fashions of the time.
At the Paris expositions and the Great Exhibition in London, Jumeau dolls received their commendations due largely to the quality of the clothing, and no special significance was attached to the dolls themselves. This changed in 1867, when at the Exposition Universelle of that year, the company was awarded a Silver Medal, and "special mention was made of the doll's heads". By 1873, when they were awarded a gold medal at the Vienna Exposition, the firm was making their own bisque dolls in their Montreuil factory.
The "Golden Age" of the Jumeau factory lasted from the late 1870s to the late 1890s, when the competition from German dolls sent the company into financial difficulties. The Jumeau dolls from the later 1890s are of more variable quality. German dolls in the 1890s were cheaper than the French, but still well-made and much loved by little girls, even if they were by no means as elegant or graceful in face or costume as the best Jumeau dolls.
The Jumeau company became part of the French conglomerate the Société Française de Fabrication de Bébés et Jouets. The S.F.B.J. still continued to use the Bébé Jumeau trademark throughout the 20th century, even producing dolls in the manner of Jumeau.
The dolls are still popular with collectors today, and can fetch quite a hefty sum.
Source and more info: Wikipedia.