Antique Victorian Rolled Gold (or Gold Filled) Bar Pin Brooch

One of a kind antique Victorian bar pin brooch. Likely from nid-1800th to late 1800th. Gold filled, or rolled gold (rose gold) on top, and still partially on the sides and the back, as pictured. Judging by the color, it can be any karat purity - 9K, 10K, 12K, or 14K. With an old style hinge and clasp that are in fully working condition. The back base, the pin and the clasp are made of white metal. It was acid tested as 10K gold, but was not confirmed by the jeweller. There is a partially visible stamp on the clasp, as pictured, and I can't read it. 4.3 cm long