The above represent some of the most common examples of gem enhancement. The industry has never felt a need to disclose treatments that are indistinguishable from the processes that occur in natural formation. However, there is one other common enhancement that falls into an entirely different category. That is the oiling of stones. Some gems, most notably emeralds, have internal fractures.
Light reflects off of their surfaces, which seriously effects the clarity and brilliance of the gem.
However, by simply filling them with a substance of similar optical properties, the tiny cavities once again become transparent. Now, how chicken this is depends on your point of view. To the gem cutter, this is a serious problem. Those tiny fractures represent areas of weakness that have to be considered in the cutting process. To the proud owner of an emerald, the improvement to it's appearance is well worth it.