Newfoundland Caribou Issue - Prussian Blue?

I have always said that these types of color/shade/hue "varieties" were cooked up by dealers back in the day to further the cause of collectors parting with their cash. And of course, the catalog companies (really Scott) were happy to accommodate their masters. There are a number of US classics that are in this category with hefty to obscene premiums attached for minor (we aren't talking red vs green here) color variations. For Russia the culprit is perforations with the Soviet Empire pumping out copious amounts of nuanced varieties (at least you can physically measure these with a $1 tool).