Even in tiny ladies' watches there can be very good movements. An example is Roamer, who put into a very small watch of only 17.5mm diameter this, unfortuately not further identificable, movement.
This MST caliber measures only 15.6 x 12.8mm (~ 7 x 5 3/4 lignes), but contains many high quality parts: a large glucydur balance, an Incabloc shock protection, an adjustable hairspring stud and a regulator with a hand. The main plate contains golden beared jewels and the anchor wheel even runs in a Diafix jewel setting.
I am glad for all hints which can help to exactly identify this movement.