Many CD 151 H.G. Co. /Petticoat insulators were used on the Chicago, Rock Island & Pacific Railroad as it ran East and West through Iowa. Most were various aqua and blue aqua colors; however, there were a few that were near clear in color. I also found the CD 151 H.G. Co. /Petticoat in rare colors including ice, cornflower blue and depression green. This post compares all three colors found in Iowa. Details are as follows:

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Medium Cornflower Blue - Measures: 88mm Wide x 104mm Height [id=618672259]

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Ice /Near Clear - Measures: 88mm Wide x 103mm Height [id=618611617]

CD-151 H.G. Co. (Front Skirt) / Petticoat (Back Skirt) - Depression Green - Measures: 88mm Wide x 104mm Height [id=618673923]

The back of these insulator are compared in the following post [id=618674634].

Footnote: I found the following reference in the ICON Article section.

https://www.insulators.info/articles/cd-151-find.htm