The Maltese Falcon isn't gold or silver or ruby-red or black or white. The Maltese Falcon is every shade of grey.
Not the statue, or the impostor made of lead, but the events and crimes and lies and hopes surrounding it. Sam Spade isn't, in spite of evidence to the contrary, the protagonist. Archer isn't the white knight martyred in search of the Holy Grail. Brigid isn't the lady in red, nor the virginal innocent in search of protection as she originally claims. Gutman may covet that which is not his, but to see his life's goal thwarted is not without sadness and irony. The creators of the Maltese Falcon, the Knights Templar of Malta (The group never existed and seems to be a symbolic mixture of the Knights Templar and the Knights of Malta, sworn enemies), weren't golden in their intentions. Joe Cairo isn't the yellow-bellied treasure hunter. Quite possibly the only person in the entire scenario without duplicity was the Kid, so full of rage he never finds a deeper meaning, but he is so transparent he has no colour at all.
Detective Tom Polhaus: Heavy. What is it?
Sam Spade: The, uh, stuff that dreams are made of.
Detective Tom Polhaus: Huh?
The Maltese Falcon is every shade of greed, of betrayal, of hope, of human nature.