A question of gold....

Merlin Dorfman wrote:
Mike wrote:

European gold (jewelry as well as gold coins when they were for
circulation) is redder than American gold. Is that beacuse copper
is used as the alloy metal? What is used in the US?


Is used or was used? Refining technology has advanced considerably and
the ratios of metal in "coin gold" these days are very consistent.

Old US gold coins have varying degree of copper and silver as admixture,
which influences the color, not only between countries, but also between
mints. This is not only due to human intervention, but also due to
origin of the gold. Keep in mind that the primary content was that of
gold, which had to remain constant, the other two metals (Cu/Ag) could
be present in different proportions with silver not constituting more
than some small fraction (I believe it was 0.05 fine). Then there are
also trace contaminants.

While the composition is a determinant in color, the quality of the gold
mixture (incomplete mixing leading to copper spots), treatment of the
planchet (acid treatment vs. not, time of treatment, annealing,
polishing, etc) and minting process (die prep, strike pressure, etc) are
also important in color and color development.

Finally, storage grime (haze) and toning of the copper and silver in the
coin over time (storage, wear, cleaning) will also influence the color.

Hence there is no concrete answer. I think Sovereigns (22 karat, .917
fine) are usually less often reddish than the US coin counterparts (.900
fine). There seems to quite a lot of difference in colors in the large
$20 coins (Libs and St.Gaudy). There is probably a lot to be said for
prior cleaning as one of the major determinants of gold tone.

I don't seem to remember seeing a lot of 9 karat jewelery in the US, but
it's quite frequent in Europe, which could account for some of the
differences one sees.

Mike

Thanks for the encyclopedic answer! I'm using personal experience--
side-by-side comparison of European and American jewelry, and comparing a
couple of Czarist Russian gold coins with American (circulating pre-1933
and NCLT since 1986) gold coins. I haven't checked a British (George V)
sovereign against the American and Russian coins but will do so.
----------------------------
Mike wrote:
Merlin Dorfman wrote:
Mike wrote:

European gold (jewelry as well as gold coins when they were for
circulation) is redder than American gold. Is that beacuse copper
is used as the alloy metal? What is used in the US?


Is used or was used? Refining technology has advanced considerably and
the ratios of metal in "coin gold" these days are very consistent.

Old US gold coins have varying degree of copper and silver as admixture,
which influences the color, not only between countries, but also between
mints. This is not only due to human intervention, but also due to
origin of the gold. Keep in mind that the primary content was that of
gold, which had to remain constant, the other two metals (Cu/Ag) could
be present in different proportions with silver not constituting more
than some small fraction (I believe it was 0.05 fine). Then there are
also trace contaminants.

While the composition is a determinant in color, the quality of the gold
mixture (incomplete mixing leading to copper spots), treatment of the
planchet (acid treatment vs. not, time of treatment, annealing,
polishing, etc) and minting process (die prep, strike pressure, etc) are
also important in color and color development.

Finally, storage grime (haze) and toning of the copper and silver in the
coin over time (storage, wear, cleaning) will also influence the color.

Hence there is no concrete answer. I think Sovereigns (22 karat, .917
fine) are usually less often reddish than the US coin counterparts (.900
fine). There seems to quite a lot of difference in colors in the large
$20 coins (Libs and St.Gaudy). There is probably a lot to be said for
prior cleaning as one of the major determinants of gold tone.

I don't seem to remember seeing a lot of 9 karat jewelery in the US, but
it's quite frequent in Europe, which could account for some of the
differences one sees.

Mike