Minecraft wiki entry for Development_versions, associated text: Crafted with honeycomb and string.
Comes with 16 dyed types and a yellowish non-dyed type.
Can be lit by any item that produces fire.
Up to 4 can be placed in a single block, similar to sea pickles, for a maximum light level of 12.
Only candles of the same color can be placed on the same block.
Only one can be placed on an uneaten cake and lit.
If any of the cake is consumed, the candle pops off.