Quote:
Originally Posted by David
I am not challenging your word here, but do wonder if their could be some mistake in your testing. I have never heard of 10-14k gold tarnishing like that. I would think that the gold level in this ferrule would have to be much lower than that for it to tarnish. It is a wonderful score regardless.
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I was surprised by the degree of tarnish too but don't have experience with old ~50% gold alloy. I used an acid-based tester (JSP). Would love to get feedback and further discussion on metal testing and hear about experience with gold alloy patinas. The way the tester works, for those not familiar, is you scrape the metal to be tested on a fine grain stone to create a streak. The acid is calibrated to different gold purities: 22k, 18k, 14k, 10k. The acid is dripped sequentially on the streaks. If the metal dissolves you move on to the next until the metal does not dissolve. In this case 14k dissolved but 10k didn't. Therefore the conclusion between 10 and 14k. The picture below is from the internet but shows what the process looks like. Perhaps I am overconfident that it was not gold plating, but here is my thinking - I removed the ferule which is fairly thin and used the bottom surface for consistent long gold streaks on the stone which reacted evenly to the acid. Unless very thick I don't think gold plating would react so evenly and I would expect the underlying metal to be apparent.