Cocktail shaker - .800 silver

On the metal part of the lid there are clearly visible two official Italian state assay marks:

The 800 mark inside an oval indicates the metal fineness. This is 800 silver (containing 80% pure silver). Note: the metal is not simply silver-plated; the lid is made of solid silver.

The Italian factory mark 197 FO inside a rectangular cartouche with rounded corners (in accordance with Legislative Decree no. 313 of 1944):

FO is the automotive/identification initials of the province of Forlì, in the Emilia-Romagna region, Italy. 197 is the unique registration number of the specific goldsmith/silversmith workshop assigned in that province.

Period of manufacture

The shape of the mark (without the five-pointed star, which became mandatory to the left of the number only after the reform of 1968–1970) indicates that the shaker was manufactured in the period between 1944 and 1968.

How does this affect the value?

The fact that the lid is made of solid 800 silver rather than silver-plated brass greatly increases both the collectible value and the material value of the item.