When you say certified, it means something real or something of value. It is something that follows certain standards and passed it. Just like pertinent documents you need when you are going to work abroad, most agencies would like those to be the certified ones if not the original.
Do you know that there are the so called certified coins too? For people who are investing in buy and sell of coins, one of the selling factors for the coin is its being a certified coin. Where could you get these kinds of coins? Go to Monaco Rare Coin Company. This company is the provider of rare coins. If you do not plan to invest and already have lots of money, you could just collect these rare coins. It would definitely have a resell value in the future just in case you would like to enter the rare coin business.