What is the most accurate way to identify a vintage item, besides asking an expert?

I'm looking for a way to accurately identify the age of vintage items (such as clothing, jewelry, kitchenware, pictures, etc.) without relying on an expert. <br><br><br>Some general rules I already know are looking out for the use of modern materials, manufacturing marks that weren't around in the claimed era, overall condition of the item, and the weight of the material. <br><br><br>Isn't there some way to actually test the age of the item?