Gold won't tarnish, rust, or corrode, and though it's very strong, it is also the most malleable of all metals. A single ounce of gold could be drawn into a wire 5 microns in diameter, more than 80 kilometers long. Pure gold is too soft to withstand the stresses of daily wear, so it is alloyed with a mixture of metals like silver, copper, palladium, and zinc to give it strength and durability. Karatage indicates purity and is noted by a number followed by the letter "k". Traditionally karatage is expressed in 24ths, meaning 18k gold is an alloy of 18 parts gold and six parts other metal. 24k gold is 100% gold with no alloyed metals. Blue Nile is proud to offer only 18k gold in all of our gold jewellery.

Gold, element Au, was one of the first known metals. Its beauty, versatile and useful physical characteristics, and scarcity help continue to make it a very valuable commodity. 24 karat = 100% gold Too soft for jewellery 22 karat = 91.7% gold Very soft – not recommended for jewellery 18 karat = 75.0% gold Recommended for fine jewellery 14 karat = 58.3% gold Recommended for jewellery 12 karat = 50.0% gold Not used in Blue Nile jewellery 9 karat = 37.5% gold The minimum standard in the UK

There are few exemptions to the hallmarking laws. One exemption is by weight; compulsory hallmarks are not needed on gold under 1g, silver under 7.78g and platinum under 0.5g. Also, the UK is required by the European Court of Justice to accept other European national hallmarks as sufficient hallmarking, providing those hallmarks represent an equivalent guarantee of quality.

All products sold by Blue Nile comply with current Parliamentary nickel regulations.

• The type of metal alloys included in it
• The percentage of each metal alloy

Gold
Our 18k gold is composed of 75% gold, alloyed with 25% other metals. Not only does this make the piece more valuable, it makes it strong enough to withstand daily wear while maintaining its traditional, rich golden colour.

White Gold
The 18k white gold at Blue Nile is 75% gold, alloyed with 25% white metals to produce a white metal with a slight yellow colour. To enhance the whiteness, almost all white gold is plated with rhodium, an extremely hard and shiny white metal in the platinum group. Depending on the amount of wear to a piece of jewellery, over time this rhodium plating may wear off, revealing the original metal colour. Re-plating is a simple process that can be done to restore your jewellery's whiteness if needed.