Why are modern gold American Eagle coins developing a deep golden toning so quickly ?

Kingplatinum

My observation is that high-karat gold (over 20K) tends to tones very slowly over many decades, if indeed it does at all.

However, I see that modern American gold Eagle coins have a tendency to very rapidly develop a beautiful deep golden tone. I most especially see this on the
1999-W American gold Eagle errors.

I am certainly not complaining, but I am also puzzled about how this could be occuring on 22K gold surfaces after literally just a few years (only five to ten years).

Thoughts?

TwoSides2aCoin

Global warming.

Not necessarily my thoughts, mind ya

Longshot

Gold coated tungsten may tone differently...

Dabigkahuna

I think it is the rinse that mint uses. Maybe?

It happens much more with PCGS holders than anything else I've seen.

Some of my proofs have turned a very nice deep dark red.

derryb

<< <i>I think it is the rinse that mint uses. Maybe?

It happens much more with PCGS holders than anything else I've seen.

Some of my proofs have turned a very nice deep dark red. >>



PCGS - Agree. ICG holders also.

Kingplatinum

... any additional thoughts, as I find this very intriguing? Could it be some kind of rinse the mint is using?

ericj96

Its the PCGS holder and copper content on modern gold...they dont mix if you like untoned coins. If you do provided they tone evenly they are the ticket.

Kingplatinum

... I find this intriguing, as I thought the PCGS holders were supposed to be inert, and not affect the coin's surfaces
(and, I would think, most especially gold) ?