For 24 Carat Gold the number 990 is used to denote 99.0 grams of pure gold per 100 grams of alloy. The figure ‘990’ thus represents 24 carat gold. Despite what some people think, it’s not very common to find pure gold items that are ‘100 per cent’ pure. The purest gold ever recorded only goes up to 999.999 purity, or 99.9999 per cent. This was produced by the Perth Mint in 1957 and assayed by the Worshipful Company of Goldsmiths in London.
This product was never commercially released however, so you are unlikely to see such a hallmark anytime soon.
Investment Gold bars and coins are often sold with a purity level of 24 carats, or gold 990 or even higher. Many investment grade minted gold bars and coins are .999 or .9999 or ‘four nines’ purity.
Did you know gold 990 was the same as 24 carat gold? While the term 24 carat gold might be more common, these two expressions of gold purity are synonymous, so don’t worry if you’re being sold gold 990 when you’re searching for 24 carat gold!
Because of its high purity, the 24 carat gold rate will be very close to the ‘pure’ gold rate or price.