btw, neptune is not an ocean of diamond, it is a gas giant, made of... i dont know... maybe gasses? and when carbon is formed into diamond, it will not melt at in earths conditions, just turn straight from solid to gas form.
my rant is over
i just wanted to say that changes to DMND would break many or most saves. TPT is neither unrealistic nor realistic in some points. so i understand your point very well, but also you have to admit that TPT would not get 100% realistic sometime. therefore i used the phrase