Hallmarking

Hallmarking

Hallmarks are small letters, symbols or numbers that are added onto jewellery items. The symbols have various meanings. They indicate:

  • the metal alloy the piece was made in
  • the place of manufacture
  • the manufacturer

The metal alloy

Jewellery made from precious metals have to be hallmarked to indicate the alloy they were made in. The hallmark indicates the amount of fine metal in the alloy. The following alloys are recognized by the South African Bureau of Standards (SABS) and these are their accepted hallmarks:

Note:

  • Platinum and palladium alloys that are not 95% pure must be stamped Pt/Pd as well as the number of parts per thousand that are fine metal e.g. Pt 900, Pt 850 or Pt 800.
  • In the United States, carat, when referring to a unit of fineness (as opposed to the weight of a gem) is spelled as karat. The hallmarks 9k, 14k, 18k etc. are also widely recognized and accepted in South Africa.

If a jewellery item is made from two different metal alloys, a 9ct yellow gold ring with sterling silver detailing, for example, then the hallmark for both alloys must be put on the inside of the ring.

Place of manufacture

In South Africa it is required by regulation that all jewellery manufactured within the borders of the Republic must be hallmarked with an encircled ZA. Other countries have their own conventions. In the UK, the mark of origin indicates the assay office (see below) where the item was verified.

Manufacturer

In South Africa it is not required for the manufacturer to mark their jewellery with their own name or logo. Many do, however, as it becomes a way to brand an item. In the UK, the maker’s mark refers to the person or company who submits the item to an assay office for hallmarking.

Who can hallmark?

In many countries, including the United States (Untracht, 1985:44) and in South Africa, the jewellery manufacturer hallmarks his own jewellery. This does not offer the consumer a lot of protection, as unscrupulous jewellers may “water down” the fine metal in the alloy, or simply stamp the wrong mark on the item, though routine checks are carried out by authorities and wrongful marking is fined. In the UK, precious metal objects must be submitted to an assay office to be hallmarked. The same applies to objects imported into the UK. The assay office checks the purity of the metal and applies the hallmarks.

Note: 

The word Hallmark comes from the historical British precious metal inspection site, Goldsmith’s Hall, in London. Items were stamped with the Hall’s Mark (Untracht, 1985:43).

Methods of hallmarking

Traditionally, hallmarks are applied to the metal surface by means of a specially made punch or stamp. The stamp is a case-hardened steel (Untracht, 1985:44) tool with a mirror image of the symbol or lettering in relief on its tip. The tip is placed in position on the item and a hammer blow to the back of the punch will transfer the hallmark to the metal. Hallmarking punches are usually bow-shaped so that they can fit into the shank of a ring. 

Tip:

To keep a ring upright for stamping (leaving your other hand free to strike with the hammer) place the ring into Prestik (Blu-Tack) with its shank supported in the groove of a swage block. Choose a groove that is similar in shape and size to that of the ring’s shank. This will minimize the damage on the bottom of the shank that may be caused by the hammer blow.

Hallmarking with a stamp
Hallmarking with a stamp.

The harder the hammer blow, the deeper the hallmark. A deep stamp is preferable as it will be clearly readable, and it will not be easily worked out by further finishing that needs to be done to the metal surface. A hammer blow that is too hard, however, may bend or distort the metal, and this will have to be smoothed out again. Because of these reasons it is often best practice to finish the metal to as close to its final finish as possible before stamping, and to only bother finishing the under side of the stamped surface after hallmarking.

Today, hallmarks are often also engraved by hand or machine, or designed into the CAD model and cast with the hallmarks in place.

Where to hallmark

Jewellery are always hallmarked in a discreet spot; the idea is that the hallmarks should not be visible when the item is worn.

  • Rings are hallmarked on the inside of the band, just to the side of the bottom of the ring. This is done so that the ring can be sized in the middle of the shank without cutting out the hallmark. Hallmarks may also be moved aside to make place for engraving on the inside of the ring.
  • Chains are always hallmarked near or on the clasping mechanisms. The clasp itself often bears the hallmark, or if the chain is particularly fine, a small tab with the hallmark is inserted between the clasp and the rest of the chain. 
  • Earrings are hallmarked on the back, unless there is no space for a hallmark. In South Africa, jewellery under 1g does not need to be hallmarked if the item is physically too fine for a hallmark to be displayed on it. This often happens with fine wire ear studs. In this case it is often good enough if the push-on that is fitted onto the earring post displays the hallmark, even though it can be separated from the earring.