Gold is resistant to rust, tarnish, and corrosion. Although gold is very strong, it’s also the most malleable of all precious metals. Pure gold is too soft for everyday wear so it is alloyed with other metals to increase its hardness. Like other precious metals, gold is measured by troy weight and by grams. When it is alloyed with other metals the term carat (ct) is used to indicate the amount of gold present. Karat (k) in the USA.
24ct = 100% gold – Too soft for everyday jewellery.
22ct = 91.7% gold – Old wedding rings and Indian jewellery.
18ct = 75% gold – Recommended for fine jewellery.
14ct = 58.3% gold – Common in America.
9ct = 37.5% gold – The minimum standard in the UK.
In general, most 18 carat gold alloys are harder wearing than their 9 carat equivalent. 9 carat gold alloys tend to be slightly brittle, whereas 18 carat gold alloys tend to be more resilient. 18 carat alloys are almost completely resistant to chemical attack in normal use, whereas 9 carat alloys are much less resistant due to their high silver content and as such are prone to tarnish. All Faller gold jewellery is made with 18ct gold.
Regardless of carat, the combination of metals used in the alloy will decide the metals colour:
18ct yellow gold is normally alloyed with silver, copper and zinc to strengthen the metal and enhance the yellow sheen.
A copper alloy gives gold a reddish hue. Faller 18ct rose gold is 75% gold, 19.5% copper, 5% silver 0.5% other which give a beautiful rosy hue distinct from yellow gold.
In general pure yellow gold is whitened with a combination of metals such as palladium, platinum, zinc, silver, and copper. The alloy mix varies depending on the physical properties required for working and the carat percentage to be achieved. White gold is rhodium plated to produce an even whiter finish. Rhodium is a highly reflective, white metal, which is extremely hard and durable. However, over time the rhodium plating wears away, revealing the usually slightly yellowish/brownish or greyish tint of the underlying metal. To keep white gold looking its best, it may require rhodium re-plating every 12 to 18 months, depending on wear. While we prefer platinum or palladium in rings which receive the most wear and tear, 18ct white gold works well for other jewellery such as pendants or earrings. All our 18ct white gold jewellery is compliant with Nickel free directives, with less than 0.05% nickel content.
There is a lot of conflicting information online describing the characteristics of precious metals. This happens because the same general terms are used to describe different metal alloys with different properties. Take 18ct white gold for example:
It is 75% pure gold and 25% alloy, (a combination of other metals that can vary considerably). What the makeup of the alloy is and how it is worked affects its colour, hardness, resistance to wear etc. Designing alloys with the best colour that is soft enough to work but hard enough to take a good shine and be resistant to wear is complex. Some of the combinations that produce the whitest white gold can be too hard and brittle. Other more malleable alloys have an unattractive colour requiring rhodium plating to enhance it. Nickel was the most popular alloy used in the past but since it has been identified as carcinogenic and linked to dermatitis it is no longer an option.
Alloys are continuously being changed and developed and this means it is very difficult to compare like for like with any degree of accuracy between different jewellery manufacturers.
At Faller our understanding of metals and their properties has been gained through years of experience in making, retailing, maintaining and repairing jewellery.