Real natural honey will experience crystallization. Some honey will crystalize at a much fast pace than others. The reason for this comes down to the flower the honey is made from. Tupelo honey has a much slower pace to crystallization than a clover or gallberry would.
Crystallization is not a bad thing and does not mean the honey has gone bad. In fact, this can be a good thing and indicate you have the real deal. Once the honey crystalizes, you can turn the honey to a spreadable whipped honey or you can "melt" it back down to its original state.
There are a few ways you can melt honey back down without compromising its integrity. But two things I don't recommend is placing honey in direct heat, i.e. directly on the stove, or in a microwave. These methods heat the honey too much and too fast which can cause important enzymes to break down decreasing the honey's beneficial properties.
1. On a hot day, you can place your bottle of honey in a sunny spot and allow the hot sun to melt away the crystals. This process is slow but is a natural method to bringing honey back from its solid form.
2. Bring a pot of water to a boil and remove from heat. Allow the pot and water to cool down for a good 4-5 minutes before placing the honey bottle into the water. This process can be repeated but keep an eye on the bottle to make sure it does not become too hot. If the bottle is too hot, the honey is too hot.
3. Keep it crystalized. Keeping honey crystalized doesn't make it unusable even if you don't want to make it into whipped honey. In fact, you can still take a spoon full and add it to a recipe, coffee, tea, or other and it will de-crystalize and incorporate into the item just the same.
The cold will always induce crystallization, so if your room of storage for honey is cold then the crystallization process will be much quicker. Keeping the honey in a warmer area will slow down the crystallization process.