Nice two-tone California signal, CD 161, in sage green and purple. Sage green is the most common California color; purple shades run second or third. The combination of the two colors; however, is unusually uncommon. The purpling is caused by the excitation of the manganese in the glass by the ultraviolet rays in sunlight. The manganese was introduced in the insulator glass batch through cullet or through deliberate addition as a de-colorizing agent. Uneven mixing of the manganese results in the surprising and pleasing swirls and patchy color you see in this insulator.