There seem to be differing opinions on the definition of sprezzatura:

http://wso.williams.edu/~espence/sprezzmeaning.html

http://www.landini.org/sprezzatura/whatitis.html

http://www.sprez.com/sprezzatura.htm

http://wordsmith.org/board/showthreaded.pl?Cat=&Board=words&Number=124831

All opinions are equal but we must remember that some are more equal than others.