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 Indian rupee till 1990, after which it was minted every following year. Stainless steel coinage of 10, 25 and 50 paisa was introduced in 1988. In 1992, a new stainless steel rupee coin, smaller and lighter than the older rupee, was minted, alongside a 5 rupee Cupronickel coin. In 2005, the 10 rupee coin was minted for the first time. Higher denomination coins were introduced due to an increasing demand for change and the increasing cost of printing 2, 5 and 10 rupee banknotes. On 30 June 2011, all coins in denominations of 25 paisa and below were officially demonetised. Commemorative coins