Picked this little guy up at the national. I've always shied away from purchasing yellow California glass (at least the non cable types) because there's no way to know if they are authentic or thermally reversed; unless they come with a strong pedigree, which is usually not the case with most yellow Cals offered in the hobby.
This example has good provenance, but that's not all, check out the glass extrusion that squeezed out of a loose mold at the right mold line. Look closely at the delicate fin of glass in the wire groove. There's also a smaller, thinner fin of glass in the wire groove at the opposite mold line. I see no way that this would have not been broken away if the insulator was installed with a wire tied to it. It's pretty clear to me that it was never installed, never used, thus never exposed to the UV rays of the sun (which would have transformed it to purple).
I'm told that this insulator was recently obtained from an elderly woman that collected insulators back in the 1960s. This same woman had several CD 130 Cal Elec Works that were removed from the famous Bodie, CA line, back before it was designated a State Park.