The incense burned during the testing ceremony is called koh. Certain colors of koh are chosen at each testing level to represent the student's path. Below are the meanings.

Gokyu - Red koh represents the beginning of the universe when there was great heat and pressure.

Yonkyu - Yellow koh represents the great light at the birth of the universe that still shines today.

Sankyu - Orange koh represents the cooling clouds of gases that would soon form stars and planets.

Nikyu - Purple koh represents the early morning of the birth of Earth.

Ikkyu - Brown koh represents the abundance of nutrients for the coming life in the soil.

Shodan - Green koh represents the beginnings of a new life.

Nidan - Blue koh represents the sky and the rain that feed the first life.

Sandan and above - Black koh represents the vastness of the cosmos and interstellar space.