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Now 18 karat gold is 750 parts of gold for 1000 parts of metal, and is the international minimum standard of quality gold in the WESTERN world.
Is that a pseudo standard, although I sort of agree, I can't say I've read it anywhere.
An interesting question - which gold is gold and which gold is crap?
We need to delve into a bit of science to dig out the answer. For a
gold alloy to have at least some properties of gold, - gold must be
dominant component in alloy, at least 50% of atoms must be gold. The
questions is how to determine that without actually counting atom one
by one, because it is kind of tedious. Analytical chemistry to the
rescue.
First let’s recall Avogadro number, which is 6.023E+23. This is a
really big number and those who unfamiliar with scientific notation,
think of it as number of dollars that even US government cannot
spent, no matter how hard they try. Avogadro number represents
number of atoms in one mole of substance. This number is the same for
any chemical entity. Sometimes it is called Avogadro Constant. So if
we take one mole of gold and one mole of silver, such alloy would
have numerically 50% of gold atoms and would satisfy criterion of
gold which is gold.
One mole ( one mole of element in grams is equal to atomic weight of
that element ) of gold weighs 197 grams and one mole of silver weighs
108 grams, which yields 64.6% by weight or 15.5k, Here goes 14k
standard, but story is even more interesting. Consider one mole of
gold and one mole of copper. Mole of gold is 197 grams, but mole of
copper is only 64 grams. So in this case minimum purity is 75.5% or
slightly above 18k. That is why 18k alloys always have some silver
present.
I do not want to drive everybody crazy with endless calculations,
but think what happens when we introduce zinc, or other metals in
alloys. By doing that, the number of gold atoms becomes less than
50%, and the gold becomes crap. That should also answer the question
about difficulty of wearing rose gold, which was posted. Also
consider how dumb the standard of 14k is. Composed traditionally of
gold, copper, silver, and some zinc ( casting alloy ), it definitely
is the gold, which is truly crap. And to add insult to injury, there
are alloys with silicon and etc. Frankly, I am amazed that people do
not loose their fingers, wearing the stuff. And 9k!. don’t even get
me started!
Leonid Surpin
www.studioarete.com