The coins that are colorized outside the RCM or USA mints cannot be graded as they should not be.
Coins may be minted by RCM or USA mints but colorized by a third outside party. They buy the coins cheaply in Monster Boxes or tubes, stick a decal on them and wham they get $100 for a $20.00 coin. These are not mint issued coins and have no value other than melt. it's to bad so many people have fallen for this trick sale. if you notice the boxes they come are not mint issued, the COA's are made up to look authentic.
Do anyone actually believe the original mints are only going to produce 100 coins, DUH !
However they keep coming out and some are very nicely done. So if you want fancy decals over your bullion coins in your collection go for it.
As for me I collect International coinage from real mints. Your first clue should be to check the NGC Registry. If you cannot find the coin anywhere, which you wont. It's a fake. We don't need a book to let us know which are fakes just use common sense.
Sorry to hear you wasted money with NGC and the price of a Maple Leaf or Silver Eagle tube coin. However you have the coins. My advice put them on eBay, possibly you can get some of your money back.
Good Luck, Bob (Charleston-Coin)