How Are Gold and Silver Coins Made?

The process of minting gold & silver coins is centuries old. Modern technology may have made minting much quicker and less expensive, yet the basic methods that were used centuries ago are still used today, albeit on a more efficient scale. Read on for your step-by-step guide to the minting process of gold and silver bullion coins.

Step 1: Designing a Coin

When a new coin is commissioned, gifted technical artists employed by the mint will firstly create and draw out a selection of designs. Once an artist’s design has been decided upon, a sculptor will then create a large three-dimensional clay sculpt. This sculpt is many times larger than the actual size of the coin in order to perfect the design to the finest detail. Plaster is then poured over the clay model to create a mould.

Step 2: Creating a Die

The plaster model is then coated with rubber which is used to make an epoxy resin mould. This mould is then mounted onto a transfer-engraver machine, which reduces the design to actual coin size, and transfers the image onto a steel blank called a ‘master hub’.

Heat treated metal is placed under a lathe and is smoothed into a measured blank die. The master hub is pressed into this die, creating the ‘master die’. This master die is then used to create working hubs, which are put through the same process to create the working dies - these are the dies used for the actual striking process. The difference between a hub and a die is that the hub has a raised image, and a die has an incuse image - one forms the other.

Step 3: Preparing the Silver & Gold

The pure gold or silver is first melted in a furnace and then poured into cylindrical billets. These billets are then made into long, thin strips and cut into smaller lengths, before being sent into a blanking press that punches the gold or silver strips into discs known as ‘blanks’. Each blank is weighed to ensure the final coin weighs the correct amount. The blanks are then washed and polished to a brilliant lustre suitable for coining.

Step 4: Striking the Coins

Each blank is carried along a conveyer to the coining press, where a steel collar is then inserted into the press around one of the dies. Hundreds of tons of air pressure push the blank into the collar, whilst the overhead die is forced down onto the blank. This large impact causes the formation of impressions on both sides of the coin, which is now ready for inspection.

Coining presses vary in sizes, from those that stamp one coin at a time, to others that stamp four coins at one time. Presses can strike from 120 up to around 400 coins per minute. 

Making Proof Coins

Proof is the best minting quality available, and is characterised by the raised motif, which stands out from the mirror-like surface of the coin. Proof coins also feature a matte or frosted finish to the design, contrasting with the shiny background, which is known as a ‘cameo’ effect. Proof coin blanks are polished and are struck using a die which has been specially polished, and each coin blank is struck more than once, giving extremely fine detail to the coin. These coins are then carefully packaged to ensure they are not touched by bare hands. Proof coins are usually supplied in presentation boxes with certificates of authenticity, sometimes fetching a higher premium than bullion coins as they are prized by coin collectors.

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