The process of minting silver coins is centuries old. Modern technology has made the process much faster and cheaper, but the basic methods used centuries ago are still used today, albeit on a more efficient scale. It has also become much more easy and cheaper to buy silver bullion.
Step 1: Designing a coin
First, a new coin is commissioned by the mint, and then talented technical artists design a selection of designs. From these, an artist’s design is chosen. A sculptor then makes a large three-dimensional clay sculpture, many times larger than the actual size of the coin, to perfect the design down to the smallest detail. Plaster is then poured over the clay model to create a mould.
Step 2: Creating a die
The plaster model is the covered with rubber, which is used to make an epoxy-resin mold. This mould is then mounted on an engraving machine that decreases the design to the coin size and transfers the image to a steel blank.
The heat- treated metal is smoothed on a lathe and formed into a measured die. The hub is pressed into this die to create the ‘master die’. This master die is then used to make working hubs, which go through the same process to make the working dies – these are the dies used for striking.
Step 3: Preparing the silver
Pure silver is first melted in a furnace and then cast into cylinder-shaped billets. The billets are cut into long, strips before being sent to a stamping press, which punches the silver strips into discs called ‘blanks’. Blanks are individually weighed to ensure their weight is correct. The blanks are then washed and polished to a high gloss suitable for minting.
Step 4: Minting the coins
Each blank is transported by a conveyor belt to the minting press, where a steel ring around one of the dies is inserted into the press. Hundreds of tonnes of air pressure push the blank into the collar while the upper die is pressed onto the blank. This strong impact creates impressions on both sides of the coin, which is now ready to be tested.
Coin presses come in different sizes, from those that mint one coin at a time to those that mint four coins at once. The presses can mint between 120 and 400 coins per minute.
How are proof coins made?
Proof coin blanks are polished and are struck with a die that is also polished. While a bullion coin is minted only once, a proof coin blank is minted more than once, giving the coin extremely fine detail. The coins are carefully packaged so that they cannot be touched with bare hands.
Proof is the best minting quality available and is characterised by the raised motif that stands out against the reflective surface of the coin. Proof coins also have a matt or frosted surface that contrasts with the shiny background, known as the “cameo’ effect. A lot of people who buy silver bullion and other precious metals prefer proof coins. They usually come in presentation boxes with certificates of authenticy that investors always appreciate