1804 Mexico 8 Reales - Need Help

Discussion in 'World Coins' started by Chris B, Jan 12, 2020.

  1. Chris B

    Chris B Supporter! Supporter

    Ok, CT friends, I need a little help.

    I picked this up today at our monthly coin show. Everything thing at first glance appears good. The weight is right on. The edge looks good. The problem is the assayer's mark.

    For 1804 Krause only lists TH (Tomás Butrón Miranda & Henrique Buenaventura Azorín) as an assayer's mark. This coin has FM (Francesco Arance y Cobos & Mariano Rodriguez). They show 1803 as the last year for the FM mark.

    So what do you think? Are there records of the FM being used in 1804? I've checked all of the normal sources but I know we have some specialists here.

    Thanks in advance for any help.

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  3. Seattlite86

    Seattlite86 Outspoken Member

  4. physics-fan3.14

    physics-fan3.14 You got any more of them.... prooflikes? Supporter

    I was just going to summon him ;)
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  5. jgenn

    jgenn World Crown Collector

    This is certainly a forgery simply based on the incorrect assayer initials. But you might wonder why it looks so good and has evidence of a fair amount of circulation. Given that you say the weight is accurate, it might actually have 80% or more silver.

    Several countries forged issues like these in massive quantities for trade with Southeast Asia in the late 1800's to early 1900s because the silver traders greatly preferred the 8 reales of Charles IV above all other silver trade coins. As the schroff's got better at measuring the silver content, forgers were forced to increase the silver content to near accurate levels. See Bob Gurney's book for the full details.

    Some other things to check, because most of these forgeries don't have obvious design flaws like impossible assayer initials:

    Look for two overlaps in the edge design. The genuine issues were made on a parallel edging mill, a Castaing machine or something very similar and they would leave a short area of overlap in two spots on directly opposite sides and the size of the overlap, generally 2-3 rectangle/circle devices, will be identical in length.

    Measure the specific gravity carefully to make sure it's 90% silver.

    Neither characteristic is a guarantee of authenticity. If you really want to be sure the alloy is correct, an XRF scan should reveal a small percentage of gold for genuine issues from the Mexico City mint. The silver mined in Mexico contains small amounts of gold and the refining techniques of that time were not capable of separating out those small amounts from the silver.
  6. Chris B

    Chris B Supporter! Supporter

    I appreciate the thoughtful response. I didn't come out and say it but being a fake crossed my mind more than once. What gets me is how "correct" it looks other than the assayer's mark. I have someone I can take it to that can do an XRF scan.

    Just to make sure I understand, you believe it to be a contemporary counterfeit, correct? Assuming it is I will probably keep it because that is still of interest to me.

    Is there any chance you have any photos of the marks I should look for? I don't believe I have ever seen this.
    Seattlite86 likes this.
  7. jgenn

    jgenn World Crown Collector

    Assuming that your example is not a recent forgery, then this is a great one to keep because it will fool most collectors and dealers at first glance. If it didn't have the assayer error, you might get some resistance from people that think they know how to authenticate these issues.

    I deliberately did not use the term contemporary counterfeit because that should only apply to forgeries made to circulate along side genuine issues at the time when the genuine issues circulated. Bob Gurney is currently describing these as "bullion forgeries" for the category of coins that were still used for their bullion value, well after their normal period of circulation.

    Here are some photos from an 1808 dated 8 reales from the Potosi mint. All the Spanish Colonial mints used parallel edge milling machines, so the two overlaps at opposite sides should show on all genuine issues from any of these mints.

    edit to add: I'll find some of Bob's posts on CCF to link to later.

    1808_PTS_PJ_8R_edge1.jpg 1808_PTS_PJ_8R_edge2.jpg
    Last edited: Jan 13, 2020
  8. jgenn

    jgenn World Crown Collector

    What bothers me most about this coin is the mismatch between the "appearance of wear" on the surfaces and the lack of wear on the edge. I'm leaning toward modern forgery -- a measurement of silver content would help greatly to determine when and why this one was made.
  9. xlrcable

    xlrcable Active Member

    Is the assayer mistake a clue to the counterfeiter’s motive? I’m thinking that “bullion forgers” might like to have a handy way to recognize their own bad coins - but if the intent is to fool a collector, wouldn’t you copy a legitimate coin as closely as possible?

    Not arguing at all, just wondering.
  10. jgenn

    jgenn World Crown Collector

    Here's a link to an excellent diagram on the parallel edging mill.

    Forgers often have multiple dies. This one is a mismatched pair resulting in an impossible date/assayer combo. I doubt it was done on purpose.
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  11. moneditis

    moneditis Reales de a 8

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