Hi, I purchased this item as it is very unusual and something I have not seen before. I can only assume that it could be just an experimental piece made by skilled craftsmen or trainees in glassblowing industry. The weight is only 140g. Thickness 0.2cm. They appears to be a pontil, however I did not expect it to be in the centre of the smaller bowl situated a third down from the outer cylindrical shape glass. the pontil measures approx. 0.5cm dia. and is concave. That's if it is a pontil. The overall height of this cylindrical shape is 14.8cm. The base/opening dia. is 5.7cm. The whole of the base area is cocave and the centre part of this (hole), measures 1.5cm. Around the rim of the hole which is the base line for the inner glass there are very small air pockets within the glass. Only the rim area of the base of this cylindrical design meets a flat surface. I would be very interested to know more about this piece, especially the method applied, but not sure where to start. I have looked at studio art glass but have not had any luck in being able to identify this. Any help will be appreciated.