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 3, 5, 10, 20, 25, 50 (naya) paisa and one rupee. Since rupees retained their pre-decimal value, pre-decimal coins of one, half and quarter rupees remained in circulation after decimalisation. The word "naya" was dropped in 1964 and a new denomination, the 3 paisa, was introduced into circulation. A 20 paisa coin was minted in 1968. Neither of these coins gained much popularity. The 1, 2 and 3 paisa coins were phased out gradually in the 1970s. In 1982, a new 2 rupee coin was introduced experimentally to replace 2 rupee notes. The 2 rupee coin was not minted again