Interesting question. We instinctively rank the precious metals in order of value as “silver, gold, platinum” like Amex cards! There is no doubt that gold, in its pure form, is worth about 60 times what silver is worth, so no contest there.
But how about the other white metals? White gold vs Platinum?
For many years platinum in pure form was worth more than gold in pure form, by quite a bit. The Platinum/Gold ratio was always a number bigger than 1. The price difference was always in platinum’s favour.
But after the 2007 financial crisis a whole new set of factors entered the metals markets. Equities declined in value, currencies depreciated, banks became unstable. Investment money went looking for a “safe haven” and where a lot of it went was into gold, driving up the price.
Meanwhile manufacturing, particularly automobile manufacturing, declined badly. Since an awful lot of platinum is used to manufacture the catalytic converters in cars, the price of platinum declined. The Platinum/Gold ratio became inverted, to a number less than 1. The price comparison between gold and platinum came to favour gold, by quite a bit.
Today platinum has finally clawed its way back to be worth more than gold, although the ratio has narrowed so both metals are worth roughly the same amount in the $1700.00 per Troy ounce range
When it comes to valuing a piece of jewellery, a different factor enters the picture: karat
Virtually no jewellery is made with a pure metal. Gold, silver and platinum are all “diluted” with other metals to make alloys. Platinum jewellery is typically made with an alloy of 95% platinum, 5% copper. So the value per gram of platinum Jewellery is typically 95% of the value per gram of pure platinum
White gold jewellery, on the other hand, is typically 18 karat, which is an alloy containing 75% gold. The other metals in that alloy are a blend of copper, sometimes silver and typically about 2% nickel to give it the white colour. European jewellery often uses palladium in place of nickel for the white colour. So the value of 18 karat gold is 75% of the value of pure gold.
You can see, therefore, that platinum jewellery is still typically worth more than white gold jewellery, gram for gram, even if the price of pure platinum and pure gold are virtually identical, because the alloy used to make platinum jewellery is richer than the alloy used to make gold jewellery