The Light property can be from 1 to 15 and determines the amount of light that the Material emits.
As a sidenote, it is kind of interesting that all Blocks in the world emit one of sixteen discrete amounts of Light (including 0)... no practical use for that, but it's very strange.
Material Synthesis
Light Emission
Мод не переведён на русский — текст на английском, как в игре. Рецепты и предметы ниже — с нашими названиями.