Unusual old porcelain cup hand painted

Saucer is scalloped shell shaped with indention on right side for "hinge" the main and the index fingers under the plate and the thumb in the upper between the other two. Cup has a cockle shape, the top is gilded that accentuates the waving shape of the border (not very comfortable to drink tea), the handle resembles a coral branch but not in red but in pale pink. Saucer and cup have inscribed wavy lines decoration. The cup has four little feet. Approx. measurements - Saucer 13.5 cm. Cup 4.5 cm high bowl 7.5 cm Made in the 19th Century.
The strange think is that it is hand painted in the outside and inside with peach flowers. Fully unmarked. There are several cups on internet that are shell shaped but they are painted as natural scallops or cockles in pale iridescent pink inside, some of them are identify as Popov or Old Paris that has two snakes as handle but are also unmarked. In addition, the Belleek Neptune cups that have small snails as feet. Nothing with peach flowers.
It is very old as suggested of the fact that there is a residue of wood ash on the back of the plate. Because of the flowers so Japanes and naturalistic shape most probably is Art Nouveau and from the last quart of 1800.
Any idea about its origin? Thanks for looking