The earliest stones, known as 'loofies', were light in weight, ranging from about 15 to 25 pounds and had no handles, instead there were hollows or niches for the fingers and thumbs and the stone was presumably meant to be thrown. Early stones were probably in use between 1500 and 1650.
Some time in the 17th century the channel stone appeared.
A rough boulder, often taken from the channels or beds of rivers,
was fitted with a handle, making it easier to throw. With the
assistance of the handle, a greater weight of stone could be used.
Some channel stones were enormous, weighing up to 183 pounds,
although 35 to 45 were more normal. Curling
Clubs spent much of their time searching for
suitable boulders to be made into curling
It was part of the strategy of the game to use large unwieldy stones to knock out one's opponents stones. By the mid-18th century however, an attempt to regularise the game led to the introduction of the circular stone, although not all the clubs were willing to conform.
The earliest dated circular stone is from Hawick, 1772. The single sole or running surface was highly polished, often with Water of Ayr stone. The stones had fixed iron handles, or occasionally brass handles. Later, removable handles were developed to reduce damage during storage and prevent unauthorised use.
Where suitable raw materials were available, there were masons who specialised in making curling stones. By the mid-19th century mechanisation was producing the highly polished circular stone familiar to the modern curler. At the same time attempts were made to produce a running surface to cope adequately with both 'keen' and 'dull' ice. In 1879 J.S. Russell of the Toronto Club introduced a double-soled stone to cope with this problem. Kays of Mauchline developed its manufacture.
Nowadays hundreds of identical stones are produced, accurate to half an ounce and polished to a splendid uniformity. Few players now have their own stones, most using those supplied by the ice rinks.
The curling stone is a durable implement. Charles Aird of Kilmarnock Townend Club played with the same pair of stones from 1842 until 1892. Stones presented to T.J.G. Stirling of Strowan in 1862 were used in the Grand Match in 1935.
The curling stone industry has never been a large scale manufacture. At its height there were only ever six or seven firms producing stones in Scotland, and there were only one or two outside Scotland.
The most famous source of raw material for stones is Ailsa Craig, a towering volcanic plug in the Clyde off the Ayrshire coast. It produced Common Ailsa, Blue Hone Ailsa and Red Hone Ailsa stone. From the late 19th century until 1952 quarrymen lived on the island during the summer months, producing between 1000 and 1400 rough blocks per year for shipment to the mainland. Quarrying ceased temporarily in 1952. In 1961 the Ailsa Quarrying Co. Ltd. Resumed production.
Today only Kays of Scotland at their factory in Mauchline manufacture Ailsa Craig curling stones, producing around 1000 a year. In 2002, supported by the World Curling Federation, the company spent eight weeks quarrying and transporting about 2000 tons of granite to the mainland to meet production needs for the next few years.