All that glitters isn't gold. I think this expression has something to do with "fool's gold." You think you're happy and have found a nugget, only to discover that what glitters isn't the gold you were hoping for. Only the magpie doesn't care for bling, and now that's true for a lot of people.
I can still remember how jewelry used to be genuine. Real silver, real gold, real gemstones. These days, that's no longer the case, and no one seems to care if what they wear is made of steel, iron, or plastic.
