Neat color on this E.S.B. Co. "Chloride Accumulator" battery rest.

The PG lists it in emerald green, but the main body of this one is dark yellow green, tending toward olive. The stem is closer to true emerald green. An accompanying photo shows a side by side comparison with an emerald green McLaughlin signal. Spec-Tru reading (bottom up through the stem) for the battery rest is 535+605+1015. I've never seen one of these in any color besides light aqua, so I don't know if this color is typical or unusual for the species. Can any of y'all shed some more light on this?