A Ring of Promise Between Baek Mir and Dan Bi?

We are all excited about this drama.What's the plot? Who's who? Where do we go next? Which station?. These questions usually bothers us. But thanks to the articles and writers who continuously giving us photo stills on what is actually going on with the drama. Because of this, even though the drama promotion isn't yet on its high content, just photos alone can make us excited more than anyone else. 
A photo in particular that somehow intrigues some eagle-eyed readers. 
These photos perhaps?

What could that be? A ring of promise do you think? As for the manwha, Baek Mir and Dan Bi are friends ever since they were young, They got separated and eventually met by accident somewhere in a ski-park. So is this could be the ring of promise to love each other forever and never forget even got separated? Interesting.