Raw honey is honey in its most pure form – straight out of the hive. It's not pasteurised, heat treated, or pressure filtered, so all the goodness is still in the honey.
Crystallisation or candying occurs naturally. Raw cold-extracted honey should form crystallisation over time because it has not been heat processed or over filtered.
The speed of how fast honey crystallises depends on the varying difference of natural occurring sugars in the flora that the bees forage on, so some honey will crystallise faster than others.