In a sentence, when I want to talk about something that isn't really important I can use parenthesis "(...)" to express how insignificant this thing is.
Your sister is very beautiful (the one who is 19 years old).
What about double parentheses? When I want to express something insignificant into something insignificant.
I put your bag on the table (the round one (at the third floor)).
Even though it is very ugly, I was wondering whether it's orthographically correct and therefore can be used in some situations.