I think that NGC went through a short period where coins were over graded and their reputation suffered a bit.
Now, they have become much harder.
As a result, if I were to sell a slabbed coin on
ebay,
I would find it easier to attract bidders with a recently graded NGC coin.
Fortunately, the whole grading, and buy / sell system has now become a bit more reliable.
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It is now up to the Chinese to find a way to fake the current slabs to a higher level of deception.
Constant vigilance is the is the best defense.