In earlier times, some people believed that the firmament was an enormous blue sapphire in which the Earth was embedded. Could there be a more apt image to describe the beauty of an immaculate sapphire? And yet this gem comes not in one but in all the blue shades of that firmament, from the deep blue of the evening sky to the shining mid-blue of a lovely summer's day which casts its spell over us. However, this magnificent gemstone also comes in many other colors: not only in the transparent grayish-blue of a distant horizon but also in the gloriously colorful play of light in a sunset – in yellow, pink, orange and purple. Sapphires really are gems of the sky, although they are found in the hard ground of our 'blue planet'.