How coins are made: from the mint to your pocket

सिक्के कैसे बनते हैं — how are coins made? In India, a coin starts as a long coil of metal in a government mint. Machines cut it into plain discs, soften them in a furnace, press the design onto both faces in a single blow, then count and bag the coins for the Reserve Bank of India, which sends them to banks and on to your pocket.

The ₹1 you hand to the kirana shopkeeper has made that whole trip. The steps also explain the small mark under the year and why some coins stick to a magnet.

Who decides which coins India makes?

Only the Government of India has the right to make coins. The Coinage Act, 2011 lets the government decide the value, size, metal and design of each coin, and it caps the face value of any coin at ₹1,000. This is why the Finance Ministry, not the Reserve Bank, announces a new series of coins.

The striking is done by the Security Printing and Minting Corporation of India Ltd (SPMCIL), a company fully owned by the government. The RBI then takes the coins over and puts them into circulation.

Where are India's coins made, and how can you tell?

SPMCIL runs four India Government Mints, in Mumbai, Kolkata, Hyderabad and Noida. Each mint leaves its own small mark just below the year, so any coin at home tells you where it was born.

A coin with no mark is therefore from Kolkata. Children doing a project on the old names of India often notice that every coin carries both "भारत" and "INDIA".

How is a coin made, step by step?

The mint receives metal in long rolled coils of the right thickness. A blanking press punches plain round discs out of the strip, the way a cook cuts rounds out of rolled dough with a steel tumbler. These discs are called blanks, and the leftover strip goes back for melting.

Punching makes the metal hard and brittle, so the blanks are heated in a furnace and cooled slowly. This step, called annealing, softens the metal so it can take a sharp design. The blanks are then washed and dried, because dirt or oil would spoil the face of the coin.

Next, a rimming machine raises a thin rim on each blank, which protects the design when coins rub together in a gullak. Finally, in the coining press, two hardened steel dies strike the blank from above and below at the same instant. The coins are then checked, counted by machine and packed in sealed bags; the Noida mint, says SPMCIL, has no blanking press and strikes blanks sent by its sister mints.

Did you know? The ₹1 and ₹2 coins are made of ferritic stainless steel, which is about 83% iron and 17% chromium. Because of the iron, these coins cling to a fridge magnet, while the copper-rich ring of a ₹10 coin does not.

What metal is your coin made of?

A ₹1 coin may pass from a bus conductor's leather bag to a wet vegetable market in the monsoon, so it needs a metal that does not rust or wear out quickly. Stainless steel suits this job well.

Under the rules notified in March 2019, the ₹1 coin is 20 mm across and the ₹2 coin 23 mm, both in stainless steel. The ₹10 coin has an outer ring of nickel brass and a centre of nickel silver, so its two colours are easy to recognise.

How does a coin travel from the mint to your pocket?

From the mint, sealed bags go to the RBI, which sends them on through its offices and currency chests, storehouses kept by banks on its behalf. Your bank branch draws coins from there for shops, bus depots and customers.

Coins of ₹1 and above are legal tender for any amount up to ₹1,000, and the 50 paise coin for up to ₹10; a defaced or badly worn coin stops being legal tender. In wedding season, banks see a rush for fresh ₹1 coins for the shagun envelope, one of many traditions of Indian culture.

Sources: The Coinage Act, 2011 (India Code) and Security Printing and Minting Corporation of India Ltd.