Del Pezzo Surfaces of degree 6 over an arbitrary field
  We give a characterization of all del Pezzo surfaces of degree 6 over an arbitrary field $F$. A surface is determined by a pair of separable algebras. These algebras are used to compute the Quillen $K$-theory of the surface. As a consequence, we obtain an index reduction formula for the function field of the surface. 
Mark Blunk