Very rare Biedermeier jewelry Victorian

Very rare Biedermeier jewelry (Victorian) / sentimental medallion (individual construction) with precious stones; extremely rare; set with 5 tourmalines in old cut (tested); Foam-gold (gold foil 14k); stamped several times / maker's mark “A&K - an“ A ”stamp and a bird (?) with a 4; a wonderful Mariage from the period 1840 - 1880 (Second Biedermeier); probably remodeled in the 1920s; it can be worn either as a brooch or as a pendant with a necklace; on the back a small showcase for memorabilia from loved ones; these sentimental medallions hold e.g. Curls, letters and small souvenirs from loved ones that could always be carried with you; first-class craftsmanship; high quality; traces according to age and use; measurements: approx. 3.5 x 6.5 cm