You can find unoiled emeralds, but many will be so light in color, you’re sacrificing on color in order to get one. The more chromium, the more deep green color, but that comes with the caveat that chromium breaks up the crystal structure. There will be more fractures, and hence more likely to have clarity enhancement. Other locations for emerald may be more likely to have less clarity enhancement, but those locations produce lighter gems and/or gems with a higher vanadium content, that also produces green hues.
Countries that tend to produce lighter emeralds are:
Russia
Ethiopia
Zambia (well darker, but more vanadium)
Afghanistan
United States (North Carolina)
There are other South American mines that produce outside of the famed Muzo mine, like Chivor in Colombia, and Brazil, but they tend to clarity enhance. I think Ethiopian emeralds, although lighter than Muzo duck neck green, look very similar to Chivor material. Zambian is my least favorite. Russia produces some glowy clean material, but much of it, not all, is very pale. Afghani stones are pretty, similar to Ethiopian in color. I would say Zambian is my least favorite, but there may be some nice examples here and there. I have yet to see a Zambian that glows though.
However, in my opinion, there is nothing as beautiful as an old mine Muzo duck neck green. If you can find an untreated one, that is the Holy Grail of emerald quality, and be prepared to pay a hefty price. Many come up to auction from old collections or sunken treasure. Even Elizabeth Taylor’s famed Muzo emeralds had faint oil (AGL).
