I think the hint "Diamond: C(s, diamond)" refers to the chemical notation for diamond, rather than standard enthalpy of formation specifically. The 'C' is the chemical symbol for carbon, the 's' stands for solid, and 'diamond' specifies which form (allotrope) of carbon is being referred to (diamond rather than graphite in this case).
Although I could well be wrong of course: perhaps someone searched for something like "notation for formation of diamond", saw the Wikipedia article with that notation in it, and got the clue that way.
All will be revealed in the fullness of time.
Dragon_Nexus said: Now if that hint *is* for Emma Frost, is that the first mutant since November 2015 when Pheonix came out?I'm curious, I looked through my roster and couldn't see a mutant character that came out more recently than her. Has it really been that long?
halirin said: Maybe fox is seeing how much the MCU tie in is helping Sony with Spiderman...
Anon said: The clue is so obvious to Emma Frost that I don't think it's her. The capital C is interesting. Crystal maybe?