Wedding Rings
The Precious Metals Used

Standards.

Gold (Au) : In England, where makes jewellery, the gold alloy standards mostly used are:
9 carat (9 parts in 24 or 375 parts gold per 1000 of alloy) - there are yellow, white and red gold alloys.
18 carat (18 parts in 24 or 750 parts gold per 1000 of alloy). - also in yellow, white and red (rose) colours.
Other UK standards are:

14 carat (585 parts gold per 1000)( is little used in the UK, and then it is generally used only for export items to countries such as U.S.A. Bullion products are quite difficult to obtain in 14K but will make some designs in yellow or white golds and now provides prices for some of these. It is likely to take somewhat longer than the same item in 18K and there may be additional hallmarking charges.

22 carat (916 parts gold per 1000) is a rich yellow gold but is quite soft compared to 18 carat and demand is small. Availability is now much less than in the past and it is generally available only in plain wedding rings made to special order.

Platinum (Pt) is normally used in a 95% standard (950 parts Pt per 1000), but, since 1999, some other platinum standards have been hallmarkable, though materials are hard to obtain. In the 950 standard, the 5% alloying metal is added to harden the alloy and would usually be copper, ruthenium, cobalt or iridium dependent on the processes used in manufacture.

Silver (Ag) comes in two classic hallmarkable standards:

Sterling silver (92.5% ) usually alloyed with 7.5% copper to give some hardness as well as a property of age-hardening.

Britannia silver (95.8%), is somewhat purer and softer and is used for enamelling and for some silverware.

Fine silver (99.9% pure) can be very soft and can thus be used for collars and collets for burnishing over gemstones or irregular objects (eg drinking horns). Electroformed silver is also very pure, but in this form it can be very strong and hard because of the crystalline structure. It is also very tarnish resistant.

Reticulation silver (~80%) is useful for forming crinkly reticulated surfaces in some work.

Palladium (Pd) is a very similar noble metal to platinum, but lighter in density and cheaper, which is (since 2007) being much used as a platinum alternative. It is similarly alloyed with 5% ruthenium or copper and similarly hard-wearing. It is not yet subject to hallmarking but will usually bear a 'PD 950' standard mark.

All manufactured precious metal objects of Gold, Silver or Platinum are subject to hallmarking if sold by importers, traders of manufacturers in the UK and must conform to the statutory minimum standards of fineness set within the UK. Unlike the marking system in the USA, where each manufacturer is registered to apply their own standard marks subject to inspections, within Britain, all "hallmarkable" items must be submitted to one of four Assay Offices within Britain at some stage in their manufacture. There, samples are scraped from the objects and these samples are subjected to volumetric or gravimetric analysis to assure their quality. More usually today, articles are subjected to electron bombardment analysis to analyse the quality.

The four assay offices, presided over by the British Hallmarking Council, are at London, Birmingham, Sheffield and Edinburgh.