There are several ways to construct the Bow Tie Block. Your picture is one of them (with a white center). Usually the center is the same color as two of the diagonal corners. Hope this helps. Here are some patterns:
http://www.quilt-lovers-guide.com/bowtie-block.html
http://www.quiltmag.com/pdf/Sept06-BowTie.pdf
http://www.quiltaholics.com/bom/bowtie.htm
And here's a paper-pieced version:
http://www.geocities.com/pcpiecers/fpbowtie3.html