Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_76 ( month VARCHAR, us__2013_ VARCHAR )

### Question ###
Which month in 2013 did the U.S. use the ruby birthstone?

### Accurate SQL ###

SELECT month FROM table_name_76 WHERE us__2013_ = "ruby"