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This looks to be a simple decanter with an ovoid body on a star-cut foot, panel-cut neck and tricorn rim. However it has a cypher beneath a regal crown. The cypher, acid-etched rather than engraved, is "I" over 'R" (or "RI"), the abbreviated latin for Rex Imperiator - King Emperor. It could also be for "Regina Imperator" - Queen Empress. The stopper is a hollow 'balloon' form with a lower band of panel cutting.
British coins minted in the reigns of Kings Edward VII, George V, and George VI have the legend "Ind Imp" among other abbreviations. India was ruled by the British East India Company on behalf of the British Government during the early 19th century but was finally dissolved in 1874. Queen Victoria petitioned Prime Minister, Benjamin Disraeli, to be given the title Emperor of India. This was because her eldest daughter, Vicky, was engaged to be married to the heir to the German Emperor and as an Empress, Vicky would have out-ranked her mother who was only a Queen! Following the dissolution of the East India Company, the Queen's petition was granted by the government in 1876.
It seems that Victorian coins did not bear the legend 'Ind Imp' until 1883.
The decanter probably dates from the final years of the 19th century or the early years of the 20th.
14.5", 37 cm. high incl. stopper.