I think it's about how she feels different from her family and unconnected with them "only thing we share is one last name". “Coal to Diamonds sold to fools” is referring to a common myth that Diamonds actually come from coal, in which they don’t, but some foolish people still believe it. I think marina is metaphorically referring her family to a messed up shady business that sell fake diamonds to fools. I think she's saying that people in her family all lie and are untruthful to each other. I think the song is about how she doesn't want to be like the people in her family and she can't relate to them.
I think it's about how she feels different from her family and unconnected with them "only thing we share is one last name". “Coal to Diamonds sold to fools” is referring to a common myth that Diamonds actually come from coal, in which they don’t, but some foolish people still believe it. I think marina is metaphorically referring her family to a messed up shady business that sell fake diamonds to fools. I think she's saying that people in her family all lie and are untruthful to each other. I think the song is about how she doesn't want to be like the people in her family and she can't relate to them.