pure gold Bars

First of all I would like to describe that it is not possible to economically and commercially obtain quite pure gold. 24 carat gold would be absolutely pure. Usually highly refined gold was 0.9995%. When we convert it to carats, it would be 23.988 carats. England is famous in good delivery gold bars are acceptable at .995 which is "only" 23.88 carats. After electrolytic refining, it became commercially economic to produce 0.99 pure gold, which works out to 23.9976 carats. The Royal familes of Canada also produce a .99999 fine gold coin, which is knwon as the world's purest gold coin. This works out at 23.99 carats. 

COMPILATION
Carats Percentage Per Thousand Decimal Pronounce
24 100 1000 1.000 Pure or Fine
23.9976 99.99 999.9 .9999 Four Nines
23.988 99.95 999.5 .9995 Three Nines Five
23.88 99.5 995 .995 Nine Nine Five

FOUR NINES
Almost all of the gold bars we sell are "Four Nines" = 99.99% pure. This is the highest purity of gold bar which is economic to produce for the investment market. Only the scientific market would need anything of greater purity, and the production costs would increase disproportionately.
Most of the time, we simply refer to them as "gold bars", and there is no need to specify the purity, as it is understood to be .9999 fine.

TRUTH
It may the gold market should be the oath taken by testigos in the courts, and that is to tell "the truth, the whole truth, and nothing but the truth".
If anybody was asked about .9999 fine gold bars were pure gold, one could answer yes or no with equal accuracy. "Yes" would be correct as any bar of 97.91% or higher purity is nearer to 24 carat than it is to 23 carat. (In the USA, gold jewellery manufacturers are legally allowed a half carat tolerance or leeway). A mathematician would recognise that this was a matter of "precision", numbers can be rounded to a number of decimal places or a number of significant figures. As far as 24 carat is concerned, there is an implication that 24 can mean anything between 23.5 and 24.5, but 24.0 indicates anything between 23.95 and 24.05. Similarly a number written as 24.00 24.000 or 24.0000 would indicate a number accurate to the penultimate decimal place, so that each of the three numbers specifies an increasing degree of precision.
The answer "no" would be equally correct but a four-nines bar (99.99% pure), is "only" 23.9976 carats, as shown in our table above.
It is natural truth, it is necessary to explain that 24 carat gold does not exist except in theory or possibly in infinitesimally small amounts in scientific laboratories. This should be followed by a statement of its purity indicating or specifying the degree of precision.