Blog Post - UK Jewellery Hallmarking
Hallmarking
12th February 2017
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Blog Post - Gold and Platinum Explained

Gold & Platinum

Precious Metals Used in Our Rings

There are several metals used in the creation of fine quality diamond wedding rings. By knowing some information about the different metals, their benefits and unique qualities, you will be able to make a better and more informed decision when purchasing your jewellery.

Gold

Technically Gold (Latin Aurum symbol Au) has the following properties:

  • Gold is one of the few elements to occur in a natural state.
  • Gold is characteristically yellow and is one of only two pure metals that are coloured – the other is copper.
  • Gold is extremely supple – a single gram can be stretched into a fine thread 3.5Km long!
  • Chemically its nonreactive (it doesn’t rust or tarnish) although it can be dissolved in nitric or hydrochloric acid.

Gold Purity

The Purity of gold is measured in Carats (ct) which is Karats (k) in the US and Germany. Pure gold is defined as 24ct and when alloyed (mixed) with other metals the resulting alloy fineness is expressed as a ratio or parts per thousand pure gold i.e.

  • 9ct – is 9/24 (0.375) or 375 parts per thousand pure gold.
  • 18ct – is 18/24 (0.750) or 750 parts per thousand pure gold.
  • 14ct – is 14/24 (0.583) or 582 parts per thousand pure gold.

Note on modern hallmarked jewellery you will see one of these fineness figures stamped on the item.

Why Gold Jewellery?

Given Golds attributes – colour, softness/malleability, nonreactive properties – it’s easy to see why it’s an attractive metal to use. However, in its pure state (24ct) its softness means it is easily dented, scratched and bent. The addition of other metals give it strength, hardness and can change its colour e.g.

  • Yellow Gold – is hardened by adding copper and silver.
  • White Gold – is created by adding silver, nickel, platinum, palladium or titanium for colour and hardness. Incidentally white gold was developed around the 1920’s as a substitute for platinum.
  • Rose Gold – is similarly created by adding more copper to the mix.

The above alloys lead us back to golds purity or fineness and hence the various carets (9ct, 18ct etc).

Buying Gold Diamond Wedding Rings

In the UK the most popular alloys of gold are 9ct and 18ct although you will see 14ct and 10ct (popular in the US) and even 22ct to 23.75ct (popular in India, Middle East, China etc).

When buying an expensive diamond ring such as an engagement ring, we recommend choosing at least 18ct gold given that the saving you will make on the overall cost of the diamond ring by choosing 9ct gold is not significant.

Conversely, when buying small diamond set wedding rings, the type of gold is important as its cost will be a significant proportion of the overall cost.#

Other considerations are appearance:

  • Generally speaking, 18ct yellow gold is more yellow than 9ct yellow gold, which in addition is very slightly stronger and harder.
  • Commercial White Gold alloys sometimes have copper added for malleability. This additional copper gives the alloy colour a very slightly yellow/brown tint. To overcome this, white gold jewellery is usually rhodium plated as rhodium is tarnish resistant and gives a good white colour. Incidentally, quality silver and platinum are often rhodium plated for the same reason.
  • For a lady, the big consideration for a wedding ring is the alloy the engagement ring is made of and its colour. Personal taste and colour aside, the alloy and fineness for both rings should be the same. Two rings will always rub together, so if they are the same metal they will at least wear evenly.
Stack of Gold Diamond Wedding Rings

Platinum

Platinum is a precious metal that is used in alloyed form to create jewellery. Despite being more abundant than gold it costs significantly more. The reason being the highe cost of mining and extracting the platinum from ore. It takes one tonne of ore to produce 1 gram of pure platinum.

The most common alloy used in jewellery production is Platinum 950, meaning a platinum alloy which is 950 parts per thousand platinum and 50 parts per thousand other precious metals in the platinum family such as Iridium, Osmium, Palladium and Rhodium.

White gold is nearly always rhodium plated to achieve a hard-white finish. Consequently, while white gold looks very similar to platinum, over time the rhodium plating will wear off and fade to a yellowish tinge. However, once it’s re-polished and re-plated it will look brand new again. Platinum, which is naturally white, will never fade to yellow but will take on a natural patina over time which is preferred by some. Like gold, platinum can be re-polished and even rhodium plated if the patina isn’t desirable. Additionally:

  • Platinum is more expensive than gold.
  • Whether considering gold or platinum some upkeep will be required.
  • Both gold and platinum are strong and durable precious metals, but, platinum is the stronger and more durable of the two.
  • Platinum is denser than gold, therefore heavier -some prefer the lightness of gold.
  • Platinum, because of its purity, is considered hypoallergenic. While gold rings do not create an allergic reaction for most people, some can develop an allergy from the nickel alloy used in its production.