This is a silver coin from the reign of Sultan Mustafa III Bin Sultan Ahmad of the Ottoman. Its dated 1171 AH. I purchased this coin during my visit to Istanbul few years ago.
Below is a brief history of this Sultan from Wiki :
Mustafa III (Ottoman Turkish: مصطفى ثالث Muṣṭafā-yi sālis) (January 28/18, 1717 – January 21, 1774) was the Sultan of the Ottoman Empire from 1757 to 1774. He was a son of Sultan Ahmed III (1703–30) and was succeeded by his brother Abdul Hamid I (1774–89). He was born in Edirne. His mother was Âminā Mihr-î-Mâh Sultan.
An energetic and perceptive ruler, Mustafa III sought to modernize the army and the internal state machinery to bring his empire in line with the Powers of Europe.
Unfortunately the Ottoman state had declined so far that any general attempts at modernization were but a drop in the ocean, while any major plans to change the administrative status quo immediately roused the conservative Janissaries and imams to the point of rebellion. Mustafa III did secure the services of foreign generals to initiate a reform of the infantry and artillery. The Sultan also ordered the founding of Academies for Mathematics, Navigation and the Sciences.
Well aware of his own military weakness, Mustafa III assiduously avoided war and was powerless to prevent the annexation of the Crimea by Catherine II of Russia (1762–96). However this action, combined with further Russian aggression in Poland compelled Mustafa III to declare war on Russia shortly before his death.
Mustafa married Valide Sultan Mihrişah (Mihr-i shah, originally from Genoa), and had two sons: Selim, son of Mihrişah (Mihr-i shah) and Mohammed. He also had five daughters, among them Hatice Sultan.
Item : Silver Para of Caliph Mustafa III
Obv : Darab Fi Istanbul 1171 AH ( 1757 CE)
Rev : Sultan Mustafa Bin Ahmad
Weight : 0.39gm
Diam : 15mm
Denom : Para
Metal : AR
Year : 1171 AH ( 1757 CE)
Mint : Istanbul
Purchased Price : USD