The greatest distinction between .999 and .9999 fine gold is the additional refinement they require and the 0.09 greater purity.
Aside from the difference of 9 one-hundredths greater purity, there are few differences between .999 and .9999 gold. But reaching an extra one-hundredth of one percent greater purity requires extra time and labor.
Value Difference Between .999 and .9999 Fine Gold
The extra hundredth of purity does not always equate to additional value. In many cases, the market demand for specific gold coins, like the .9167 fine Gold American Eagle will be greater than for coins will .999 or .9999 fineness.
From lower purity Gold Eagles to high-purity Gold Maple Leafs, one ounce gold coins contain one troy ounce of gold.
Refining Process Differences Between .999 and .9999 Gold
While every refinery may have its own unique methods, refining gold from .999 to .9999 millesimal fineness requires more steps and labor for the refiner.
The Miller Process
The Miller Process for refining gold utilizes chlorine gas and results in gold that is typically .995 pure but does not reach .9999 purity.
In the Miller process, chlorine is blown into molten gold, which reacts to form gold chloride, making it easier to separate the impurities. After that, the gold chloride is heated, and the chlorine returns to gaseous form, which it releases, leaving only the gold and as much as 0.05 impurities.
The Wohlwill Process
The Wohlwill process utilizes electrolytic cells to refine gold and can produce gold that is .999 fine and .9999 fine, depending on the purity of the gold anode used.
The Wohlwill process takes place in a cell holding aqua regia, a solution of nitric acid and hydrochloric acid in a ratio of 1:3. A gold ingot of .950 or greater purity is placed in the aqua regia and used as an anode. Small sheets of .999 or greater purity gold are added to function as cathodes.
Current is applied to the Wohlwill cell, and as electricity traverses the electrolytic solution, gold in the anode is dissolved. Through ionic transfer, pure gold is plated onto the gold sheets, acting as cathodes.
After the anode is completely dissolved, the cathode is removed from the solution. Then the cathode may be melted, alloyed with another metal, or processed in another manner for another application.
What Gold Coins are .999 Fine?
What Gold Coins are .9999 Fine?
- American Gold Buffalo coins
- Canadian Maple Leafs produced since 1982
- Gold Kangaroos from the Perth Mint
- Gold Swans from the Perth Mint
- Somalian Gold Elephants minted at the Bavarian State Mint in Germany
- Gold Philharmonics from the Austrian Mint
- Gold Britannias from the British Royal Mint
What Gold Coins are .99999 Fine?
Coins like the commemorative Klondike Passage for Gold from the Royal Canadian Mint are 99.999% pure gold.
What is the Minimal Millesimal Fineness for Investment Grade Gold?
While this will vary from nation to nation, in the United States, gold must be 99.5% or .995 fine for use in gold IRAs (Individual Retirement Accounts). An exception is made to this for Gold American Eagles, which are .9167 fine.
Gold Krugerrands, which are also .9167 fine, are not eligible for Gold IRAs.
What is the Threshold for Fine Gold?
Since it is technically impossible to achieve a 100% gold purity outside of a lab environment, the highest purity that is commercially available is .99999 fine.
Gold with .99999 purity is available from the Royal Canadian Mint in commemoratives. .999 and .9999 are the most common forms of fine gold.
Gold with .9167 fineness is considered fine as well. This includes coins like the Gold Eagle, British Royal Mint’s Sovereign, and the ever-popular Gold Krugerrand.
What Should I Invest In?
At the end of the day, a one ounce Gold Canadian Maple Leaf and a one ounce Gold Libertad both contain 1 troy ounce of gold. Where it concerns numismatic value, it is a matter of preference since graded coins are not eligible for investment in Gold IRAs.