The holographic trend has been sweeping over instagram for the past weeks, but what is it? Holographic hair is a mix of a silvery base with sheer, opalescent colors layered on top. The result is something out of this world. The style it's endlessly customizable, but most people go towards the violet, lavender, and blue shades. You can make it as subtle or outstanding as you want it. Either way, pastel colors tend to fade really quickly, so you'll have to take really good care of your hair with color-saving products.