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_34 ( us__1912_ VARCHAR, us__2013_ VARCHAR )

### Question ###
What was the U.S birthstone in 1912 when in 2013 the birthstone was amethyst?

### Accurate SQL ###

SELECT us__1912_ FROM table_name_34 WHERE us__2013_ = "amethyst"