A mixture of tin and copper, bronze has been used for thousands of years to create both full-sized statues and smaller figurines through the process of casting -- i.e., pouring the molten alloy into a mould. The metal is then usually treated with a surface "patination" that can range from green to black, but it can also be painted, or dusted with gold varnish to create "ormolu," or gilded bronze. Bronze is often confused with cheaper alternatives used in the production of figurines such as spelter -- an allow of zinc and lead -- and resin, a form of plastic.
Lift the item in your hand. Bronzes are extremely heavy. By contrast, spelter and resin are both comparatively light, but they are sometimes attached to heavy wood or stone bases to give them extra weight. Turn the item upside down and determine if it feels top heavy -- if it does, it's not an authentic bronze.
Examine the item for patches where the patina, paint or gilding has worn through, revealing the base metal. On genuine bronzes, wear will reveal a brassy yellow colour. Grey indicates spelter and red or brown points to resin.
Check details such as facial features, fingers and so forth. An authentic bronze will hold a great deal of fine detail, while at the same time having a smooth, regular finish. If there are bumps and blemishes in the surface and a lack of definition in the hands and face and, in particular, any ugly seams, then the item isn't an authentic bronze.
Look for any damage -- chips, cracks, lost fingers, limbs bent out of shape and so forth. Bronze is extremely hard and therefore unlikely to display any damage at all other than to the surface patina. Spelter, on the other hand, is weak and brittle.