Over the years, one of the most popular stones for interior design has been granite. But what exactly is granite? An igneous rock called granite is created when magma beneath the surface of the earth slowly solidifies. Its red, pink, grey, or white color comes from the quartz and other minerals that make up its composition. When magma can't escape through volcanoes or earth cracks, granite forms. The liquid becomes imprisoned, gently cools, and forms into a stunning stone.