An ounce on the scale: why a Krugerrand weighs 33.93 g

Put a Krugerrand and a Maple Leaf on the same scale and they disagree by almost three grams. Both hold one troy ounce of gold. Both are right.

A dealer’s page gives a coin two weights and they are not the same number. The gross weight is what the coin weighs: metal and whatever it is alloyed with. The fine gold weight is how much of that is gold. Between them sits the fineness — 999.9, 916.7, 900 — the thousandths of the coin that are the metal you are buying.

The one-ounce coins split into two camps. A Maple Leaf, a Philharmonic, a Britannia and a Kangaroo are struck in 999.9 gold: the coin weighs 31.1035 g, which is the troy ounce, because there is nothing else in it. A Krugerrand and an American Eagle are 22 carat — copper in both, silver as well in the Eagle — so the mint adds alloy on top of the ounce rather than mixing it in. The result weighs 33.93 g and still holds exactly one ounce of gold.

• Krugerrand — 33.93 g gross, 916.7 thousandths, one ounce of fine gold
• American Eagle — 33.931 g gross, 916.7 thousandths, one ounce of fine gold
• Maple Leaf, Philharmonic, Britannia, Kangaroo — 31.1035 g gross, 999.9 thousandths, one ounce of fine gold

The alloy is not a shortcut. Pure gold is soft enough to mark with a fingernail, which is why a Maple Leaf travels in a capsule and a Krugerrand can be handled; copper is what makes the Krugerrand hard and gives it its red tone. It costs nothing in gold and buys a coin that survives being a coin.

It matters here because every comparison on this site is made per gram of fine gold, never per coin on the scale. A price is only comparable once the metal has been divided out of it — which is what the premium over spot is.

Gross weight, fineness, diameter and thickness for every coin in the catalogue are on the coin’s own page, beside the prices.