The video shows how an artist makes an Ishtalinga

Ishtalinga is an indispensable means for the practice of Shiva-yoga. It is made of light grey slate stone which contains and generates electricity. To be kept intact, it is coated all over with a fine durable paste made of certain ingredients. The colour of the paste is indigo or blue-black. The colour of bhrumadhya chakra (i.e., agneya chakra or brow chakra) is also indigo.

Ishtalinga is placed on the palm of the left hand so raised as to come in line with the centre of the eye-brows. Behind the back and just above the left shoulder an oil-fed lamp or candle should be placed so that the light of the lamp is reflected in the coating of Ishtalinga. With half-closed eyes and without blinking one should fix his attention upon the Linga, the coating of which is blue-black or indigo serving to widen and deepen concentration. The colour of the paste and the colour of Agneya Chakra, being akin in nature, they act and react upon each other thus generating electromagnetic waves which dash against the pineal gland situated in the third ventricle of the brain. The pineal gland is present in everybody and although it is dormant it can be stirred into action by the process of Shiva-yoga.