Complex sentence: The Kollur Mine (or Gani Coulour) in the Guntur District in Andhra Pradesh, India, was one of the most productive diamond mines in the world and the first major diamond centre.
Split into simpler sentences: The Kollur Mine (or Gani Coulour) in the Guntur district of the Indian state of Andhra Pradesh. It was one of the most productive diamond mines in the world and the first major diamond centre.