There are new and recent vintage mannequin hands out there made to look like old ones, but this is a real one that has clearly been around the block, or more likely, around the studio. Mannequins are not my expertise and you may be a better judge that I am (so much variation among them, including from Italian to English to French to American, which is part of what makes them interesting.) But on a little comparison to other examples out there (shape of hand, construction of joints, carving of finger nails, etc.) and on the screws, wooden pegs and nails, I would guess mid 19th century. Photos give a good and comprehensive sense, including of the manners in which the fingers can be manipulated.
9 3/8" l x 3" w x 2" t. Much worn as evident, clearly much used, with surface and stain wear where it should be. Thumb and first finger are jointed in two places, while rest of fingers just at the bases, with limited movement (as constructed.) No losses, joints move as they should.