@ThePonyTheorist  
None of the other dragons ever questioned him using the magic letting him send notes to Celestia. On top of that he was able to message Amber back and forth as well (although off screen).
 
 
@redweasel  
Not create, brought back to life. If there was already a dead dragon In there she wouldn’t have to create anything.

@ThePonyTheorist
 
orrrrr maybe there was a young filly too stupid to figure out the test was to see how she handled failure, who then had a magic surge so powerful, she created spike from a stillborn dragon inside a dud egg.

@redweasel  
What he eats while on the show should at least be somewhat representative of what he eats normally. The gems found in the gem-cave also do not include copper, which is an important note.
 
The fact that he’s the only one breathing green fire could because of his magic interacting with unicorn magic somehow (likely Celestia’s), to make the teleportation-effect work - but who knows.

@ThePonyTheorist
 
if the only think spike ever ate were the gems in the show, he’d have starved before season 2. but uh, there’s nothing wrong with your hypothesis either. except that magic is an excuse for everything.
 
what’s interesting to me is that spike is the only dragon who breathes green fire.

@redweasel  
If you check what gems Spike’s eating and try to identify them, you find that copper isn’t an option. The only possibility there would be is if there were a lot of copper impurities.

@Frustration in Excelsis
 
yeah, spike just has a lot of copper in his diet.

@Frustration in Excelsis  
To quote a previous response:
 
Yes, though this is disproving one of the theories being that it’s heat making it green – still, according to my analysis in the description, I don’t think magic should contain anything in a green spectra – unless he’s burning something else, but even that seems unlikely to me?

You don’t need magic or spells to make fire green – plenty of compounds naturally burn green in their own right. The association between a specific compound and the color of its flame is precise enough that it can serve as a way to test for a specific chemical’s presence. Antimony, boron, barium, copper, copper salts, tellurium, thallium, vanadium and tungsten all burn in shades of green. One of the easiest ways to see green fire is to burn a magazine – the compounds in the pigments turn some of the flames green as long as the magazine keeps burning.

@neo4812  
Purple magic, like Twilight’s. Spike’s fire is only green due to his magic.

but ember has purple fire explain that

@Dizzy Strings  
In antiquity gem stone were considered to be the purest source for magical powers and more powerful than the bones of big animals. Ever wondered why wizards had crystals everywhere and shamans wore bones?

@mathprofbrony  
Yes, though this is disproving one of the theories being that it’s heat making it green - still, according to my analysis in the description, I don’t think magic should contain anything in a green spectra - unless he’s burning something else, but even that seems unlikely to me?
 
 
@Dizzy Strings  
re: gems being solidified magic -
 
https://derpibooru.org/1425301?q=uploader_{3Atheponytheorist  
https://derpibooru.org/1411095?q=uploader}3Atheponytheorist  
https://derpibooru.org/1413035?q=uploader_{3Atheponytheorist  
https://derpibooru.org/1413095?q=uploader}3Atheponytheorist

The first half of this theory I’ll take at face value. Gems being a source of magic I’m a little more iffy on, my understanding being that magic is just a power that all creatures generate and harness naturally.
 
Although given that gemstones being a conduit for arcane power is nothing really new in fantasy settings, it has legs to stand on at least.

Fire is not a blackbody, though. You can see green fire if the green wavelengths are its primary emission component. Boric acid in methyl alcohol will do it. (Spike can probably make methyl alcohol biologically but might eat borax as a regular mineral in the rocky portion of his diet.)
 
(ETA: Although of course his fire is magic, I’m just saying that blackbody radiation isn’t the only reason for something’s color.)