Metallurgical assay and the U.S. Mint continue to produce precious metal bullion coins for collectors and investors. The precious metal purity and content of these coins is guaranteed by the respective mint or government, and, therefore, the assay of the raw materials and finished coins is an important quality control. In the UK, the Trial of the Pyx is a ceremonial procedure for ensuring that newly minted coins conform to required standards. Metallurgical assay A metallurgical assay is a compositional analysis of an ore, metal, or alloy. Some assay methods are suitable for raw materials; others are more appropriate for finished goods.
Coins of the rupiah have the Arabic removed, with "INDONESIA" replacing its Jawi equivalent for the second minting of the coin, dated 1955 (the 50 sen was also minted that year). Inflation meant that the smallest denomination to be minted after 1954 was the 10 sen, which likewise had Arabic removed from its reverse for its third minting, 1957; 25 and 50 sen coins were also minted in 1957. After 1957, the cupro-nickel 50 sen was debased to aluminium, the same metal as the lower denomination coins (which were never minted again). As a result of this, the 50 sen, previously the heaviest, but