quote:
I'm curious, why black out the certification number?
NGC has a Registry where collectors can post their collections, based on grade, to rank against the collections of others. All a Registry member has to do is enter a certification number to put that coin in their Registry set, regardless of whether they actually own it nor not - NGC cannot track who actually owns their coin, and there are many Registry-quality slabbed coins out there which aren't in a Registry set yet.
The certification number is blacked out to keep some unscrupulous collector from adding that number to their set, thereby increasing its' quality. You'll find the same thing with PCGS slabs on
ebay.