But that's not the main point of this posting. The main point is that there are seven Chaos Emeralds, but there used to be 14.
Right, so at the end of Sonic the Hedgehog 2, Sonic has the seven Chaos Emeralds in his possession, he's defeated Dr. Eggman, yay. Now, at the beginning of Sonic 3, Sonic still has them, runs into Angel Island, and Knuckles steals them. That's all fine and dandy. But no one ever really stops to think why Knuckles would steal them (aside from being an ass). And that's because Knuckles thinks he's stealing HIS emeralds back.
In the Japanese Sonic 3 manual, Knuckles' origin goes into how he is guardian of 7 Chaos Emeralds, and that they all vanish when the Death Egg strikes into the island. And because Eggman tricks Knuckles, our favorite echidna thinks he's just taking back what is rightfully his. So during the course of the game, Sonic eventually reclaims one set of the Emeralds, and then entering the Hidden Palace Zone, a reaction occurs, having the emeralds become enlarged, fitting in their proper locations around the Master Emerald. And so the next seven special stages are him powering up the "Super Emeralds," basically joining together the two sets, giving them their proper form and all that. That helps explain why the Chaos Emeralds look so different between the Mega Drive and Dreamcast.
Just to help tie everything together, in the past segments of the Mystic Ruins, the Chaos Emeralds are plainly seen sitting around that game's Master Emerald shrine. And they are quite huge, if you fly up there with Tails or climb up with Knuckles. They are as big as...say, the Super Emeralds! And yet through the rest of the game they are palm sized. The only time you see any huge emeralds are in the past segments of Sonic Adventure, and in the Hidden Palace of Sonic & Knuckles.
You could go on to say that there were two sets, one light and one dark, which was caused by Perfect Chaos' first attack...but that didn't actually happened during the battle in Station Square. But then you could argue that the ensuing battle didn't give the emeralds the chance to split again before they were restored. But this whole paragraph is pure fanwankery.
However, that doesn't change the fact that it was stated explicitly in the Japanese manual that Knuckles guarded his own set of Chaos Emeralds, and that in the course of the game you end up with only one set of emeralds that look different than the Chaos Emeralds from the first two games, and which maintain that style through the rest of the series up to this point.
And I can't be the only one who knows this here. Because I've read people talk about it before. So yeah...am I just crazy, or is this not common knowledge?