There IS a difference between Grafenkrone and untitled nobility (the link again, pay attention to pearls).https://de.wikipedia.org/wiki/Rangkrone
But that`s of less importance in this particular case. The point is the quality of craftsmanship. Hohenzollerns are one of the oldest Royal houses and their fortune was enormous at the time, Prussia being among the most powerful kingdoms in Europe. They were prince-electors of the Holy Roman Empire (Kurfürst in German).
In short, your snuffbox is a nice 18th century example, but it cannot be attributed to any royal house and let alone to Hohenzollern.