This song is from the film Gentlemen Prefer Blondes, which was actually a production of Broadway before it was the movie in which Marilyn famously performed "Diamonds Are A Girl's Best Friend", meaning that these lyrics are not necessarily the "original" since it was first part of the Broadway musical. However, since this is under the artist of "Marilyn Monroe", there is no need to scrutinize whether the "Tiffany's" part and all is in the song, because undeniably, it is there.
But if you wanted to debate whether it was in the song in the Broadway production, you might have yourself a good argument.
This song is from the film Gentlemen Prefer Blondes, which was actually a production of Broadway before it was the movie in which Marilyn famously performed "Diamonds Are A Girl's Best Friend", meaning that these lyrics are not necessarily the "original" since it was first part of the Broadway musical. However, since this is under the artist of "Marilyn Monroe", there is no need to scrutinize whether the "Tiffany's" part and all is in the song, because undeniably, it is there.
But if you wanted to debate whether it was in the song in the Broadway production, you might have yourself a good argument.