All gold is not created equal. Well, not after its purity is diluted. There are different alloys classified as 18K and 14K, with different properties and colors depending on the metals used in the mixture. Copper, silver, and gold all have the same basic crystal structure which makes them ideal for combining. 100% pure gold is designated 24K, so 18K is 75% pure (18 divided by 24 is .750) and 14K is 58.5% pure. The following are typical ratios followed by the resulting color achieved. 18K 75% gold + 25% silver = green 75% gold + 16% silver + 9% copper = pale yellow 75% gold + 12.5% silver + 12.5% copper = yellow 75% gold + 9% silver + 16% copper = pink/rose 75% gold + 4.5% silver + 20.5% copper = red 14K 58.5% gold + 41.5% silver = green 58.5% gold + 34% silver + 7.5% copper = green-yellow 58.5% gold + 26% silver + 15.5% copper = pale yellow 58.5% gold + 30% silver + 11.5% copper = yellow 58.5% gold + 19.5% silver + 22% copper = pink/rose 58.5% gold + 9% silver + 32.5% copper = red The standards for gold colors per ISO 8654 1987[E] use a simple rating system. There is some leeway in what mixture certain manufacturers use however. 0N = 14K green-yellow 1N = 14K pale yellow 2N = 18K pale yellow 3N = 18K yellow (some manufactures do call this rose) 4N = 18K rose/pink (rose & pink are mostly interchangeable) 5N = 18K red 8N = 14K nickel white (white gold has many more variables and will be discussed in another post) Even though the same color designation is used, different purities can yield slight changes in the shades. For example, here are two yellow gold watches from the late 50's in nearly identical condition: on the left is an 18K case and on the right is a 14K case. Manufacturers choose their alloy combinations and not all used the same formulas. Some other metals can be substituted for 1 - 2% of the silver to change the finished product's characteristics. Zinc is the most common additive and will increase gold's fluidity while in a molten state. This facilitates easier cast molding. The addition of nickel will increase strength. Iridium and/or cobalt will refine the grain. Rolex's patented Everose uses platinum to enhance the appearance and resist tarnishing.
Fascinating research…Thank you I never knew the precise composition, of the different shades Ever considered Academia ?
ROFL! Seriously? How quick do you think I'd be booted out, probably removed by security, for chastising a millennial snowflake for entitled behavior?
The other case metal we're seeing a lot of now is Sedna which came out on the Constellation piepan re-edition piece and is a palladium / copper alloy similar to the platinum/copper Rolex alloy mentioned in the OP.
