Can gold coins appear slightly different in color?

[Xtal]

I have gotten a couple of gold coins off of goldmart.com

My husband noticed that they are very slightly different in color.  I noticed it, too, after he pointed it out.  They're very similar, but one is more golden in color while the other is just very slightly duller or pinkish.  The newer one (2004) is the duller coin, while the older one (1995) is brighter.

Is this normal?  It seems to me that there could be some variation in gold's natural color due to trace impurities or whatever, but I just don't know.

I'm planning to buy a gold coin balance, but I do not have one yet.  I weighed both coins on a food scale that measures in grams and they weigh exactly the same.

EDIT: these are American Gold Eagles

[HB Reader]

I have gotten a couple of gold coins off of goldmart.com

My husband noticed that they are very slightly different in color.  I noticed it, too, after he pointed it out.  They're very similar, but one is more golden in color while the other is just very slightly duller or pinkish.  The newer one (2004) is the duller coin, while the older one (1995) is brighter.

Is this normal?  It seems to me that there could be some variation in gold's natural color due to trace impurities or whatever, but I just don't know.

I'm planning to buy a gold coin balance, but I do not have one yet.  I weighed both coins on a food scale that measures in grams and they weigh exactly the same.

EDIT: these are American Gold Eagles

I have noticed some minor variation in mine (SA Krugerrands and American Gold Eagles) over the years.  If they weigh the same I wouldn't worry too much.  Neither of them is 24 carat gold, so it may be some slight variation in the alloy. 

Back in the 1970's I bought and sold some one hundred ounce silver bars that looked a little different too.  The purchaser in Dallas (who I'd bought them from a few years before) didn't seem to care, but he did weigh them both.   

[dualstow]

Some of my krugerrands vary a bit. They are not all exactly the same.

[AgAuMoney]

Weight being the same is important.  Hopefully your scale accurately or at least repeatedly resolves to at least tenths of a gram, preferably hundredths.  Personally on a one ounce piece I go for thousandths (3 decimal places) and smaller pieces need more resolution.

In addition to weight you need to check size (diameter is easy, thickness is harder).  With three coins you can use a very straight metal ruler across all three to get a rough idea.

Finally, color of a 22kt or 90% coin varies a lot depending on the composition of the remaining 8-10%.  Typically Krugerrands have used copper for nearly all the alloying material.  That takes some of the yellow out of the gold and adds pink/brown.  Gold AEs typically allow with a significant amount of silver which makes the gold appear more yellow or brighter.

However over time the allow can vary and even a 1% shift from copper to silver or silver to copper will drastically change the resulting color when you compare two pieces side by side.

Wikipedia has a good article on colored gold, with a very nice triangle diagram of the various mixes between gold, copper and silver:  http://en.wikipedia.org/wiki/Colored_gold