Local a posteriori error estimates for pointwise gradient errors in finite element methods for a second-order linear elliptic model problem are proved. First we split the local gradient error into a computable local residual term and a weaker global norm of the finite element error (the "pollution term''). The local residual term is bounded in a sharply localized fashion. In specific situations the pollution term may also be bounded by computable residual estimators. On nonconvex polygonal and polyhedral domains in two and three space dimensions, we may choose estimators for the pollution term which do not employ specific knowledge of corner singularities and which are valid on domains with cracks. The finite element mesh is only required to be simplicial and shape-regular, so that highly graded and unstructured meshes are allowed.