UFO Sighting in New Delhi, Delhi on 2015-03-24 00:00:00 - It was almost diamond shaped with dark sides reflecting sunlight from the west

It was almost diamond shaped with dark sides reflecting sunlight from the west moving slowly from west towards south east. it was evening around 5:45 or 6:00 pm. the movement was slow and gradually it disappeared towards south east. i was actually observing aircrafts coming in to land at delhi airport from my balcony. aircrafts pass at a distance of 3-4 kms away at an altitude of around 2,500 feet when i observed this strange object moving slowly a little far above may be around 4,000 feet. it gained altitude slowly and disappeared. i was able to observe it for around 20 minutes.