Usually it will say what type of pewter on the bottom of the piece. British pewter, or if it has a symbol of a crown is lead free. Most European pewter is lead free. Another feature of old pewter is the weight. Because lead has a much higher density than tin, lead-containing pewter is heavier. The more lead is added, the heavier it gets. Lastly, Newly-made pewter containing lead tends to have a bluish tint. This fades away as the pewter ages and it becomes a darker silvery-grey in color. That's due to tarnish, and the main culprit is lead which gets oxidised pretty easily. Modern pewter tarnishes more slowly and is also more easily cleaned.