Quite simply, stackable rings are rings that stack up on top each other. They stack one on another and you wear them all on the same finger like a pile of pancakes.
They become a set.
Now any rings could really be considered ‘stackable‘, I mean you could stack up anniversary bands (which would work well).The point is, there are no set rules when it comes to stacking rings. It’s all in what you like (and how many you feel comfortable wearing).