There are not published standards for polished concrete, but it is generally agreed that the concrete must be polished through the sequence of disks ending with 1800-3500 grit diamonds to be considered polished concrete. At this level the concrete will exhibit a glossy sheen and high reflectivity without the use of a topical coating.
Polished concrete in not simply exposing the rock in the concrete mix then applying a sealer.
During the polishing process an internal impregnating sealer is applied. The sealer sinks into the concrete and is invisible to the naked eye. It not only protects the concrete from the inside out, it also hardens and densifies the concrete. This eliminates the need for a topical coating, which reduces maintenance significantly (versus if you had a coating on it).
When Demmert and Associates brings the concrete to a full polish, they never apply a topical coating or wax. According to Greg Demmert, "Waxing the surface would be defeating the purpose of a fully polished floor because the concrete floor itself is already shining, so there is no need to put something on the floor that would then need to be maintained."