Bars generally carry lower price premiums than gold bullion coins. However larger bars carry an increased risk of forgery due to their less stringent parameters for appearance. While bullion coins can be easily weighed and measured against known values to confirm their veracity, most bars cannot, and gold buyers often have bars re-assayed. Larger bars also have a greater volume in which to create a partial forgery using a tungsten-filled cavity, which may not be revealed by an assay. Tungsten is ideal for this purpose because it is much less expensive than gold, but has the same density (19.3 g/cm³).