Selenite which is kind of  translucent crystal allows the flame of the candle to flicker slightly through the walls of the candle holder. Edges of the candle holders are rough which is natural to selenite. 
 
Selenite Candle Holders are shiny and sometimes with whiter areas. Top of each candle holder is polished and the underside is cut flat.
 
Weighs approx 280g, and don't forget, crystals may vary in size, colour and weight!