We use the term stone mainly for people's weight.

I always find it difficult watching a film where a person's weight is described in pounds as I have no concept of a person weighing 150 pounds but would find a ten or eleven stone person easy to imagine. It is further complicated by the fact that schools have been teaching metric units for years and we are told our childrens' weights in kilogrammes and are measured in kilogrammes in hospitals. (Not surprising as we buy petrol in litres and drives for miles.)

I have not come across stones being used for objects. For example we would have bought coal by the ton, delivered in hundredweight (8 stones or 112lb) bags. Twenty hundredweight make a ton. I note from my dictionary that in the USA this is known as a long hundrewight and a long ton, a short hundredweight being 100lb and a short ton being 2000lb - are these terms used?