It looks to me like blue 'goldstone', which is an artificial glass commonly sold in 'new age' rock & gem stores as tumble-polished pieces. Traditionally, it has been reddish brown with small glittery golden inclusions as a result of the use of copper salts and particulate copper to colour it. More recently it has been produced using cobalt instead of copper, which gives a strong blue colour and a more silvery appearance to the inclusions.