Quote:
Cricket balls are made from a core of cork, which is layered with tightly wound string, and covered by a leather case with a slightly raised sewn seam. The covering is constructed of four pieces of leather shaped similar to the peel of a quartered orange, but one hemisphere is rotated by 90 degrees with respect to the other. The "equator" of the ball is stitched with string to form the seam, with a total of six rows of stitches. The remaining two joins between the leather pieces are left unstitched.
For men's cricket, the ball must weigh between 5.5 and 5.75 ounces (155.9 and 163.0 g) and measure between 8 13/16 and 9 in (224 and 229 mm) in circumference. Balls used in women's and youth matches are slightly smaller.
Cricket balls can bounce pretty high, but the wicket (the surface they are bowled on, rather than the actual wooden wicket) is pretty hard, too.
And a macro photo of a seam:
http://photos.runic.com/cricketball.html