I don't know about metal work specifically, but Ottoman industrialization was far, far behind industrial capacities of Western Europe. Daniel Quaertart's Ottoman Manufacturing in the Age of the Industrial Revolution is notably quite short. The first pages are available from the Library of Congress. There were very few processed goods sent for export, though some processed goods did better on the local markets because Ottoman producers knew "local taste" better.

But production was TINY. Quaertart notes that official estimates for 1913 suggest that all factories in the Empire--public or private--had about 36,000 employees, total. Which is a very small number compared to the factories of the industrial belts of Europe and the Americas. The biggest industry, as in many places, seems to be textiles.

I would therefor assume that this was brought back from somewhere else (whether from Southeastern Europe, North Africa, the Middle East, an exposition in Western Europe or possibly even a pilgrimage to Jerusalem, I have no idea) as a knickknack or a keepsake, and I would be very surprised if it was part of a well establish import trade simply because the Ottoman Empire exported so little in terms of finished goods in the 19th century. The only mentions in Quaertart's book of "silver" are three references to silver thread used in embroidery and one to wages paid in silver coins.

You say 18th century in your title, but they say 19th century in the thread, so I went with that. This story changes slightly if it's the 18th rather than the 19th (as the Empire had more domestic production due to fewer European imports), but still, large amounts of exports of finished goods seems just as unlikely.