This is an antique, early 20th century style cast metal lamp that has a blackened surface patina and an onyx stone embellishment at the base. It is topped with a leaded or stained glass 'Tiffany' style shade. The shade was likely made and added later in the 20th century and the lamp may have been reproduced later in the 20th century as well (a view of the electrical plug end that goes in to wall and the light bulb holders may help in establishing age. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' can be higher and vary.