Black 7 knob candle for ritual work and to focus energy. Seven knob candles are commonly used for ritual work that spans 7 days, with one knob burned for each day of the spell. Styles vary.
Color can play an integral part in adding extra oomph to spells and rituals. In color magick, black is associated with grounding, wisdom, learning, protection, safety, reversing, uncrossing, unhexing, repelling black magick, banishing negativity, releasing, shape shifting, defense, scrying, and pride.