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Message:: [QUOTE="Rob Woodside, post: 3117627, member: 96187"]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.[/QUOTE]