The diya is an earthenware or clay lamp made with a wick stuck in a cotton ball and bathed in buttermilk or vegetable oil. Although it is used mainly during religious festivals such as Diwali or Kushti, many families have a habit of lighting one each morning and another each night, since it is considered to represent the victory of good over evil and represents the redemption of the individual from the divine power, thereby shedding earthly materialism and cunning. You have all the information in: «Indian customs«.
You have all the information in: "Indian customs".