Interactive Dreams took a pretty good stab at how to identify fake "Demonstration Disc"s, but I've had a hankering to do a guide with more pictures.
Behold, a real / official Philips CD-i Demonstration Disc.
White Label "Demonstration Disc"s are particularly vulnerable to faking, because A) There are known to be real / official Zelda ones and B) Blank, White Label CD-Rs are available to buy readily.
Print your own Zeldas and you too can become rich!
So how do we know what is real and what is fake?
Here's a look a a couple tell tale aspects of a real, official White Label Demonstration Disc.
Above: Unlike white label CD-Rs, Demonstration Disc labels don't extend all the way to the edges, leaving a silver ring at the center and the outside. Sometimes the center ring is slightly off-center even, which is fine.
Additionally, you'll notice that the above color of the data side is a clean silvery color, whereas CD-Rs usually have an aqua or rainbow color:
------------------------------QUIZ------------------------------
Here's a question you won't find in 3rd Degree, which of the following sets of discs off eBay are real and fake?
Set A