A platinum bar in assay is a .9995 fine platinum bullion bar that comes sealed in a certified assay card, which verifies its weight, purity, and authenticity. These bars are produced by reputable mints and refineries, such as PAMP Suisse, Valcambi, and the Royal Canadian Mint. The assay card includes a unique serial number, adding an extra layer of security against counterfeiting. Platinum bars in assay are a popular investment choice due to their lower premiums over spot price, high liquidity, and ease of storage, making them an efficient way to invest in platinum.