Should I use a colon or a semicolon in the following sentence?

Question

Unlike the fictional character, Gaby didn't control gravity:/; gravity controlled her.

Should it be a colon or a semicolon? Why?

Answer 1

You can make a choice between a colon and em dash, not a semicolon.

A colon can be used between independent clauses when the second explains or illustrates the first.

An em dash can be used when you want to emphasize the conclusion of your sentence.

Check out this excellent punctuation guide for Colon and Em dash. As for why you should not use a semicolon, none of the uses for a Semicolon fits your requirement.