Summary
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
99.99 .9999 same thing
Four Nines
Almost all of the bars are "Four Nines" = 99.99% pure. This is the highest purity of gold bar which is economic to produce for the investment market. Only scientific market would not 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.