Indian, late 18th - early 19th century.
Measures 4.4cm in length (excluding loose bail).
The body originally would have been extensively decorated with colourful enamels which are now mostly absent, the diamonds and rubies all remain intact.
For a similar example see the last image, sold by Noonan’s Auctioneers, JEWELLERY, WATCHES, ANTIQUITIES AND OBJECTS OF VERTU, 15 September 2020, Lot 202, sold for a hammer price of £3,400. It was described as: A late 18th-early 19th century enamelled gold hawking whistle, possibly Indian, of tapering cylindrical form, decorated all over in red, white, green and blue enamel in a foliate and floral design with scalloped borders, suspended from plain suspensory loop, unmarked, total length, including loop, 42mm.