Rugby Jersey's or shirts as they are now more commonly known, were until recently always manufactured from cotton. However, with the advent of cheaper far eastern manufacturing the more affluent teams now wear polyester and lesser sides a mixture of cotton and synthetic fabrics.
The latest shirts are figure hugging with little or no collars or buttons they are also designed to remove the water from the body quickly to aid cooling. The first examples of these shirts were worn by New Zealand and England during the season before the 2003 Rugby World Cup.
The designers also planned that they would be harder to grip and tear resistant but several England players showed that under the tough conditions of a rugby park the first versions were not quite as resistant as hoped. The technology of the shirt is still developing and it will be interesting to see what innovations if any come forth over the next couple of years.