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<p>[QUOTE=&quot;Dafydd, post: 26689656, member: 86815&quot;]Welcome to CT [USER=177404]@dtaso1516[/USER].&nbsp; Firstly, I must admit I know nothing about the design and history of these coins and in fact couldn&#039;t identify the obverse from the reverse! I assume that the gold standard of these coins is high so we can eliminate chemical reactions such as oxidisation and leaching. I used to run a non-ferrous foundry business for many years so know a little about dies and their structure and wear albeit we were casting not forging.</p><p><br /></p><p>The &quot;rippled&quot; or granular texture you noticed in the lower-right area of the reverse (the side with the knotted designs) is a known phenomenon in hammered coinage. Based on your description and the visual evidence, here are some of my ideas but I am no expert but there will be someone here for certain who is. I&#039;ll simply set the ball rolling for you.</p><p><br /></p><p><b>Die Rust or Deterioration:</b> Even dies made of hardened steel were susceptible to oxidisation if stored in damp conditions. When a die rusts, the steel surface becomes pitted and when a coin is subsequently struck the gold is formed into these tiny pits in a raised or granular texture on the finished coin. The fact that you have die paired could intimate that the die was corroded in that area and used on both planchets.</p><p><br /></p><p><b>Die Fatigue:</b> As dies reach the end of their life the constant stress of hammering causes the steel to flow or develop microscopic fissures. This can manifest as a pebbled or orange-peel texture particularly near the edges where the pressure is greatest.</p><p><br /></p><p>&nbsp;<b>Planchet Imperfections:</b> In the 16th century, gold planchets were prepared by hand. If the gold was not perfectly refined or if the planchet was poorly cast before being hammered, it might retain internal gas bubbles or &quot;sponginess&quot; that surfaces under the force of the strike. I don’t think this is the case as you appear to have a unilateral issue in the same quadrant.</p><p><br /></p><p><b>Environmental Factors:</b> While gold does not corrode in the traditional sense, it is a soft metal. If the coin was buried in a high-energy environment (like a riverbed with abrasive sand), it could develop &quot;micro-pitting.&quot; However, this usually affects the entire surface rather than just one specific area of the die. I have several “Tiber recovered” roman coins and their surface commonality lend me towards modern chemical intervention for “improvement” and attracting the romantic unwary (me!). These all exhibit a mottled surface.</p><p>I also collect shipwreck coins and sometimes we see a coin that is more eroded on one side or quadrant than the other. This is explained by the possibility of only one side being exposed to current and abrasion facing outwards or perhaps half a coin protruding from coral or sand.</p><p><br /></p><p>I have a book on the metallurgy of coins and many British Numismatic Journals which often contain articles on metallurgy. If no one gives you better answers, when I have time, I will do a little research and revert.</p><p>I suspect a die issue, third party grading gives comfort about the obvious such as casting on the first coin and the quality of the dealer should give comfort on the authenticity of the second coin. They have been around for 150 years and it would be unlikely they would let a forgery slip through the hands. It happens of course but given the provenance and reputations at stake, unlikely. Had it been acquired from certain other auction houses I would not register such positivity.</p><p>Thank you for raising an interesting first post![/QUOTE]</p><p><br /></p>

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