It was called the 'jewel in the crown' of the British Empire.
India was termed 'the jewel in the crown' because it was the most valuable of all British colonies. Britain exploited India for natural resources and India provided cheap labor. India's location was of great importance to the British as well, enabling Britain to trade by sea with foreign ports, explore more regions and bring home exotic goods like the gunpowder from China.
The British exported from India pepper, silk, porcelain, spices, tea and coffee. These goods were obtained cheaply in India and then sold at elevated prices back home in Britain.