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Coin and Paper Money Collecting/Questionable gold - Saudi Gold Guinea


large brown smudge on gold coin
large brown smudge on  

smaller brown smudge on gold piece
smaller brown smudge o  
During the 1990's, I bought a few dozen Saudi gold guineas whenever I visited the gold souks in Riyadh, KSA.  Some were loose; some were sealed in individual packets.
I noticed that some of those coins in packets have developed brownish smudges, which make me worry if it is rust -- and hence not really gold.
I was repeatedly told that the souks in Riyadh are held to highest standards, and any that do not sell "real gold" are severely punished.
Well, can you tell by the pictures what might be going on with some of these coins? (I'll try to attach as many pics as possible).


Hi Steve,
I have seen this before on gold coins. It's typically the result of some residue that was on the coin. Under normal circumstances it would have turned dark quickly, but since they are in air tight sealed packages the process takes much longer. Everything else about the coin looks just fine.
Thanks for the question! :)

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Dmitry Livshits


My specialty is world coins from the 18th to 20th centuries, primarily non-US foreign coins and related areas such as errors and exonumia (tokens, medals, etc.). I can answer questions relating to identification, grading, selling, preservation and evaluation of such items. In addition to catalog value, I can give you the practical market value and trends for specific types of coins. I will also take questions regarding counterfeits (both modern and antique) and on how to identify them. I am NOT knowledgeable in paper money/banknotes, ancient or "shipwreck" coins. Thank you.


Collector of world coins since early childhood. Access to a variety of auction records and reference material. You can also find me on Facebook.

A.S. in Psychology (2006), B.A. in Forensic Psychology (2008), M.A. in Forensic Psychology (2011).

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