These bars are stamped with unique serial numbers and individually wrapped . Johnson Matthey silver bar is an easy, inexpensive way to invest in silver. This box is most commonly left blank on counterfeit bars, or may have a laser . Genuine Johnson-Matthey bars have a stamped serial number on the front of the bar. Serial numbers have been observed in the following ways on Johnson Matthey Bars and Assay Cards: (Includes: Gold, Silver, Platinum & Palladium). does johnson matthey still make silver bars.johnson matthey silver bar serial number lookup.11 1 ounce jm bars with capsules serial numbers. WEIGHT CLASSOBVERSEESTIMATED MINTAGE1ozJM Crossed Hammers Logo. (20 ounces total).No longer in production. This auction is for TWO bars, due to the consecutive serial numbers, I will not break them up.