Thank you for all your input.
"Formal to me" is like these. My son is going to private elementory school this summer, and I will attend the opening ceremony. Or, to my friend's wedding.
So, I think I can't take vernis. Although it's super beatiful, it's too flashy for me, I think. I wish this bag could be with me for a long long time.
Please seriously consider the Epi Alma in Black. I have this bag and it is perfect for this. It is classy, refined and elegant. It is suited perfectly for these types of events.