This kind of diffusers had been relatively popular to create a delightful ambience in the home or workplace.
The diffusers are usually earthenware (sometimes glass or porcelain).
Candle burners usually has opening cut out at the sides to allow free flow of air for candle light which is placed inside. When using this kind of burner, it is necessary to take some precaution such as placing the burner away from curtain or combustible materials to avoid catching fire. Ample ventilation are also necessary and avoid using in enclosed environment.