There are several different processes of jewellery manufacture, which will determine the durability of your article. This is because the alloying process will differ depending on whether the item is hand fabricated, cast, die struck, or electroformed.
Discussed below are the various manufacturing methods as well as problems that can arise in the casting or assembly of jewellery items.
When a ring is truly handmade, or hand fabricated, all the pieces of the ring are entirely manufactured, assembled, joined and finished by hand, using hand tools only. This process creates the most durable and unique item, depending, of course, on the skill of the craftsperson.
One of the reasons for this is because the precious metal is alloyed differently than cast metal is. This is because when items are hand fabricated, the precious metal is rolled or drawn down into wire, rods or plates and then shaped into final article. The alloyed precious metal must be strong enough to withstand this labour intensive process of jewellery manufacture.
This Mayoral Chain link was entirely hand fabricated by Richard Donnell.
He has had the honour of being The Jewellers to the Christchurch City Council for since 1971 and have handmade five links in total for the Mayoral Chain.
Most jewellery manufactured these days has been cast. This is because it is a process used for mass production, as well as for one-off pieces. A wax casting is made, either from an original jewellery model, or a computer aided design process (CAD-CAM).
The wax copy is then encased in an investment (a plaster-like substance that withstands high temperatures), which is then heated so that the wax melts, leaving a cavity like the original design. Then molten metal is poured or injected into the cavity and allowed to cool. The investment is removed and then the piece is assembled and finished.
As you can appreciate, the alloyed precious metal needs to be able to flow easily when melted, in order to be successfully injected or poured into the investment. This means that the finished item will not be as durable as one made from an alloy that gets turned into a hand fabricated article.
However, casting allows for mass produced and therefore more affordable jewellery items.
This 9ct gold kiwi charm has been manufactured using the lost-wax casting process.
The CAD/CAM process
CAD/CAM is another process of jewellery manufacture and reasonably new in the industry.
CAD/CAM stands for Computer Aided Design/Computer Aided Manufacturing and combines computer technology with lost-wax casting.
The jewellery item is designed using three dimensional imaging computer software and once it meets approval, the lost-wax casting process begins.
This jewellery manufacture process creates articles that can be more unique and detailed than the traditional wax making methods. Depending on the skill of the assembly bench jeweller, CAD/CAM produced articles can also be of a high quality standard.
This ring is being made using the CAD/CAM process. A three dimensional image of the ring allows changes to be made to the design before being lost-wax cast.
A modern day coin is a good example of die striking. A steel pattern, or die, is specially made to create a particular jewellery article or component, such as a claw setting for a gemstone, or the link of a chain. The die usually consists of a punch and a mould. A sheet of metal of the appropriate thickness is then taken, and blanks are cut out by the die striking machine. Sometimes the finished item is made up of more than one piece, so assembly is required before finishing is applied.
This sterling silver
St Christopher charm
has been manufactured using the die striking process.
Die striking achieves styles that are strong and lightweight. The process subjects the precious metal sheet to tremendous pressure, so therefore the alloy must be able to withstand this. The result is that a denser, more durable metal is produced as its molecular structure becomes compressed.
This method of jewellery manufacture is particularly economic for mass produced, identical items, because it is less labour intensive than other methods.
Wax copies are created, and then painted with a thin coating that is electrically charged. The wax copy is then submerged in an electrically charged liquid that contains previous metal particles. These particles are attracted to coating and stick, in layers, to the wax copy. When the required thickness of precious metal is achieved, the wax copy is removed, and the article is heated. The wax melts and drains through a small hole in the precious metal shell.
This method is not used for ring settings, or items that are designed to be worn regularly, as it is not as durable as lost-wax casting or die striking. It is often used for large, hollow, lightweight jewellery items, such as earrings, charms such as this gold bear to the right of this text, pendants, and some necklaces and bracelets (usually where people want a large look but don’t have a lot of money to spend).
Although electroformed articles are strong, they are subject to dent, so must be treated with as much care as fine bone china or a delicate silk blouse.