Grading Services for the Amateur Collector

Thanks so much Jim. I've observed flow lines in 8 Reales pieces, but on a much larger scale that really do look like a flow, quite different than these subparallel tiny rills. These are exactly the kind of "mountains" I was expecting. So mint lustre is the sheen from the specular reflection off the flow lines. That helps a lot!!!

If you drop a particle into a flowing fluid of the same density, the particle will trace out a flow line as it moves with the fluid. I suspect the actual flow of metal during striking is perpendicular to the tiny subparallel rills and these rills form like surface ocean waves due to an uneven flow.

I'm rapidly coming to the conclusion that apart from coatings, including amalgamation, wear is the only way to destroy mint lustre. The abrasive lines I'm expecting with cleaning may be just too small to see with the naked eye or even 40x available to me. If that's true, how do the graders tell the difference between a "light cleaning" and almost no wear? Do they look at coins at 400x or more where the characteristic abrasive scratches from cleaning should be obvious?

 

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Jim, Have you any 400x photos of a "cleaned" coin?

 

No, I haven't done cleaned coins. As far as I know, most graders use a 5X-7X magnifier to grade coins ( maybe a little more for varieties or such~ although I do not know. Actually most cleaning may be done with minor depth scratches. however they disturb the reflection of light enough to be detected with little or no magnification. Cleaning is most noticeable on proofs or other similar coins. Microscopic corrosion areas can also disturb the lustre Or alter it in such a way we perceive it as Toning as they are both chemically active processes.

 

Thank you very much Jim. I now understand mint lustre, but I'm puzzled that I can't see any scratches let alone hairlines on a couple of gold coins that have lost their mint lustre in some places and graded as cleaned. The fellow I got one coin from, got it as "lightly cleaned", thought himself it was "lightly cleaned", and had it regraded, coming back as "cleaned". So this is not some single grader's error. I was hoping there might be something obvious, like abrasion scratches easily visible at 10x. Being a newbie I'm probably missing something. I just hope it is not the experience gained from a life time of looking at coins. I'm already 70!

There were technicians using the green colour of a solution to analyse for nickel. The engineers thought they had a better method that gave them another decimal place. So they came to the technicians and asked them to run the two methods on the same samples as a check. When they told the technicians that the new method was ten times better, they laughed and said they could give another decimal if desired. So they ran the test, the techies gave them another decimal place, and the new method was scrapped. The point being that if you spend a lot of time discriminating colours, you get very good at it and see things an untrained eye won't Maybe that's my problem here.

 

I wouldn't waste my time trying to determine how a cleaned statement is applied to Gold coins. I just received 6 Liberty Double Eagles back from one of the top 2 TPG. All 6 coins had a lower MS Grade than the previous other top TPG, but one was assigned AU DETAILS CLEANED. It had previously been assigned MS, but now without any alterations, gloved handling, had a statement that couldn't be determined by inspection with a loupe. It had a weak strike, and terrible bag marks, but no sign of wear on the devices, rim, or stars, with even "cartwheel" throughout on both sides.

A Gold coin can be scratched with a lubricated lightly applied Cotton Q-tip, and be seen by the naked eye upon rotating the coin, tilting to a light source. I normally use a 5X - 10X magnifier, where virtually any abnormality will be observed.

@Insider recently had what I believed was an excellent explanation of how to examine a coin. I'd suggest you PM him, as I respect his professional postings before most others. If you catch him out of an emotional state, his explanations can be stellar also.

JMHO

 

Thanks Balanced, that is very interesting. That's exactly my problem I can't see any cleaning evidence but the mint lustre is worn away in places.

With fossil specimens it is acceptable to add, or even draw in, missing bits. With mineral specimens you can remove things, but not add anything. So it is acceptable to remove iron stains, leach away matrix with acids, and clean with harsh chemicals. With coins you can't even clean the damn things without losing half the value!

The epithet "cleaned" is half as bad as the epithet "faked" But really if you can't see evidence of cleaning why worry about it?

With minerals, it is like a repaired specimen. Often the repairs can be so good you'd never notice them with out a scope and knowledge. Still these specimens are considerably decreased in value.