A candle flame has 4 zones. These different zones are:
1. Dark zone: The dark zone is the area around the wick of the candle flame that consists of unburnt wax vapour. When you ignite the candle, the molten wax moves up (due to a phenomena called the capillary action) and vaporizes around the wick creating a dark zone. This part is 'dark' because of the decomposed carbon particles formed due to vaporization. Also, it is the least hottest of all the four zones.
2. Luminous zone: This part of the flame is the region where incomplete combustion takes place and a lot of heat is generated. In this zone, the molten wax particles further vaporize in the presence of wax and vapor particles. This zone is present near the base of the flame. This part of the candle flame is typified by a yellowish flame.
3.Non-Luminous zone: The non-luminous zone is the region of complete combustion. If you look at a candle flame closely (just don't go too close), you will see an 'aura' formed around the candle. Since this is the zone of complete combsution (as there is plenty of oxygen present around the candle), it is also the hottest part of the flame.
4. Blue zone: Just at the base of the flame you will observe a 'bluish hue'. This is due to the incomplete burning of carbon dioxide resulting in the formation of carbon monoxide.