The last stage of the separation process is to examine the separated particles under the microscope to determine what maceral group they belong to. This is not simple to do with such small particles, and requires special training and careful and tedious observations. It's not so much that it is better, but that it offers more flexibility as to how macerals can be separated. What technique is used depends on the end use of the macerals. DGC also is capable of high density resolution, since the density of the solution is varied in a nearly continuous manner.
Resolution is controlled by the gradient design.
Since the separation can be directly observed, it is also easy to see if aggregation is occurring. However, density gradient techniques become unwieldy when large amounts of macerals are needed. At the left is a typical densigram from a high volatile bituminous coal obtained from the Pennsylvania State University Coal Bank. In this picture it is easy to see the three maceral groups separating. Notice that these bands are broad.