The mark on the right — "F/12L" — is identified in an article by Werner Schmidt in
Weltkunst magazine as one of a series of marks of unknown purpose which appear on 19th century Hamburg silver. These marks, not illustrated in Schliemann, are in the form of an archway (probably inspired by the archway in the Hamburg city mark where the assayer’s letter appears) and include a letter, the fineness, or both. Known examples of this “archway” mark include:
“F/12L” (items dated 1839 and, here, 1832; “12L” = 12 Lot = .750), with “FENCKER”, for Johann Friedrich Fencker (1780-by 1839), concession 1834, succ. by Wwe. Fencker [Schliemann #C 65]
“H” (ca. 1850), with “T. HASS”, for Johann Heinrich Theodor Hass (1819-after 1869), citizen 1846 [Schliemann #G 265]
“L/12” (item dated 1847; “12” = 12 Lot = .750), with “HESS”, for Ananias Hess/Hesse (1802-by 1863), concession 1832, citizen 1834 [Schliemann #C 53]
“S/730” (ca. 1865; “730” = .730 fineness), with “J. A. NOTZKE” for Immanuel Adalbert Notzke (1831-ca. 1864), citizen & master 1855 [Schliemann #680]
Schmidt postulates that these marks were applied by the maker, and may therefore be some sort of trademark. I tend to agree with this theory, but Schmidt suggests that they could conceivably be some sort of date, fineness or suburban mark. I note that the “FENCKER” mark Schmidt illustrates is not the same one here, being in block capital letters, not script. But I think there is little doubt that your spoon is by Johann Friedrich Fencker of Hamburg.
Refs:
Werner Schmidt, “Hamburg”, in
Weltkunst July 2000, v. 7, pp. 1284-1286.
Erich Schliemann & Bernhard Heitmann,
Die Goldschmiede Hamburgs (Hamburg: Schliemann, 1985), pp. 539, 559 & 562-563.