[quote=@jeroukoo]
[@KatherinWinter]
I think his explanation would just be it's magical, like most other things in this RP XD Correct me if I'm wrong, [@Blizz]
[/quote]

I understand you, KatherinWinter. As from my point of view it looks like you wanna have "magic" be explained and not just be a thing. 

My explanation for the blue fire would be that it comes within a power of the gem holder and since it lies inside of the gem holder it is not able to burn living cells or the gem holder would burn from inside. While it does burn any material like paper, it can not bring any harm to living cells. Which would include plants too but that's a thing discuss-able. 
So for that sake the blue fire would be a power wich can only connect with non living things. That could be a plus if you don't wanna harm anyone but probably also a minus in a fight when you can't set your enemy on fire. 

Anyways that's just my quick thinking right now.