There are some official regulations regarding curling stones, which are also known as rocks. All curling stones must be of circular shape and no stone can weigh more than 44 lbs., this includes the handle and bolt. There are lighter stones available for children. The circumference of the curling stone can’t be more than 36 inches and it can’t be less than 4.5 inches in height. The bottoms of curling stones are concave rather than flat. Stones have evolved over the years and the best ones are currently made of special granite called ailsite that is found only in Wales and Scotland. The earliest known curling stones came from Scotland, and are presumed to date back to 1511. When curling was first beginning to develop, the stones used were often taken from the bottoms of rivers because of their round shape and smoothness. In the 1600s, handles were attached to curling stones, which allowed players to rotate the stone as they released it.
