The answer is that not all Emeralds are treated, but the vast majority of them are. It’s like the heat treating of Sapphires… Assume they are treated until proven other wise.
There are a lot of treatments being done on Emeralds. I do not in practice have any major problems with people treating gemstones and selling them in the trade, as long as the treatments are disclosed.
Some of the treatments are very questionable and I recommend against them for anybody. A lot of people do not find these things a problem, Emerald dealers especially.
You will have to make up your own mind. Here are my opinions.
Oil treatments – There are a lot of different oils being used, including colored oil. It is supposedly an accepted practice to use Cedar Oil (colorless).
I have some definite issues with oiling gemstones and just do not find it acceptable. A lot of people in the trade will tell you it is fine. I do not like it. This is a difference of opinion. I recommend against buying any gemstone that has been oiled.
The main thing(s) I do not like about oil are:
Oil hides flaws and improves color. Which is of course, why they do it. I have some ethical problems with this, because it is done to “improve” a stone and hide flaws.
How much has the Emerald been improved/oiled and will the Emerald dealer tell you? If they even know? Because of oil, you cannot really tell what the stone quality is, usually to the loss of the buyer. Often the treating on the stone(s) was done a long time before the Emerald dealer (or person selling it) acquired the stone and they really have no idea what was done to the stone(s). So assuming they are honest they just plain do not know what has been done to the stone.
If oil is filling and hiding flaws (that is the reason oiling a stone is done), the stone may be a lot more fragile than it appears and not suitable for jewelry. In my opinion, if a stone has been oiled I do not think they are worth buying.
Basically if a stone is oiled, I would not buy it, period, walk away from it. Especially compared to other stones available, see below.
Oil will wear off of, and out of the inside of any stone it is used on sooner or later. It is not permanent. When the oil has worn off of the stone, it will look terrible (usually). Also keep in mind if the stone wears (Emerald will usually not wear well because of the flaws in them), and if you need to fix a chip or do any re-cutting, the oiling will be a problem. The fresh cuts (fixed facets) will usually not match the rest of the stone, and the stone will need to be re-oiled to get it to look decent again. This costs money and time, and a lot of cutters will not even consider re-cutting an expensive Emerald, because of the problems and liability involved. I will not re-cut an Emerald.
I have heard Emerald dealers compare oiling Emeralds to heating Sapphires, and saying it is the same. Not True, the color(s) obtained in heating Sapphires are basically permanent, and will not wear off. Heating is also a natural process that occurs in nature (it should still be disclosed). Oiling does not occur naturally and as far as I am concerned is not acceptable. Ever hear of stones coming out of the ground already oiled?
Other Treatments Opticon – It is a plastic polymer resin that is injected into and onto (often under vacuum) Emeralds, both rough and cut stones. This treatment is more stable, although it will yellow and disintegrate with age and some solvents. It fills flaws and helps improve color and some durability (again why they use it). I am more neutral on this, as long as it is disclosed and a price adjustment has been made (lower).
Note: Emeralds are often also oiled after the Opticon and other treatments. Again oiling is not acceptable in my opinion.
New Processes – There are several new processes available that are basically secret in the trade (similar to Optican, but without the problems, they hope…it’s too early to tell yet). Again I do not really have a problem with this kind of treatment, as long as it is disclosed. These stones of course should be not as highly valued as a natural untreated quality Emeralds, if such a thing really exists.
The only Emeralds that I have ever seen that I thought were pretty nice natural and untreated, were from the Zambian mines and I have not seen a lot of those (Zambian material can be, and often is oiled). I should mention I probably could not afford (more like did not want to pay the price when I consider what that kind of money will buy in other stones) the ones I did like. Most all of the Colombian material I have ever seen has not been particularly good, oiled, included, flawed. That does not mean there are not some good ones, I just have not seen many.
Remember the reason that all of these treatments are done in the first place is to “improve” Emeralds, i.e. color and clarity. Do you really want a stone that has been “improved” and if so… How much “improvement” is OK? Where does it stop?
Emeralds and Flaws A dirty stone (flawed/included) is a dirty stone (sorry guys), I do not care if it is an Emerald and accepted practice in the trade to call them good quality. Yes, I know GIA’s system separates stone types into categories and gives them different definitions of clarity depending on the type or category. It is just my opinion, but I do not agree with that current grading system.
I realize saying they are really flawed, would impact selling Emeralds and other stones, that is my point. I know Emeralds do not occur clean and flawless and that what is considered a good Emerald clarity wise is still included, there is nothing wrong with that.
But my point is they are included. I do not agree that there should be a separate clarity grading categories for Emeralds, or other stones. They will still be worth what they are worth, because they are Emeralds (or whatever) and that is how they occur in nature.
In my opinion grading Emeralds and other gemstones to a different standard in the system I mentioned above is not a good idea and it is confusing. That is the main problem I have with this grading system… I do not agree with them on some other issues either.
For Example… Take a piece of Aquamarine (which is in the same Beryl family as Emeralds) with a VS clarity and really quite clean. You probably would not see anything with your naked eye unless you have a lot of training.
Now… Take an Emerald (it is not a VS in my opinion, flaws can be seen by the naked eye) being called a VS clarity using this system, but in a different “type” than an Aquamarine. An Emerald will actually be pretty included in comparison to the Aquamarine.
But by using a different definition of clarity, and sorting the gemstones into “Types” (i.e. Type 1, Type 2, Type 3…) They are defining an Emerald as being in a different Type (because of clarity) than Aquamarine, but still calling it a VS clarity for that Type.
Confused? Bet you are, that is my point. They are defining what the stone actually is and are truthful, but you will need to be careful and read the fine print. What is more important you as a customer will need to under stand the grading system. Very, very few people out side the stone business know the system.
How many customers read the fine print and know there are actually different categories? These things are published and with a little research should be easy to find (look in my “just ask Jeff” section), but…
In my opinion there needs to be a simpler way to do it. Why not always make the clarity grade consistent for everything, all types of stones? That is what I prefer to do and how I usually grade my cut stones, although I do have some stones that I have had certified by a GIA Gemologist. Usually at the request of a customer or jeweler that I do business with.
If you are getting the idea that I do not recommend Emeralds, you are right. I think that there are a lot better stones to buy, especially for the money… (see below)
I really do not cut man-made rough very much, but I think Gearloose (a well known person on the web) probably has a very good idea on the hydro thermal Emerald (man-made). If you really want to cut Emeralds. Cut the thermal man-made Emeralds. Truthfully it really would make a good replacement, especially when you consider all the dye, oil and treatments going on in Colombian (especially, but also other localities too) Emeralds.
I can just hear people saying no give me the dyed and plastic one instead of the man-made???
Other Alternatives to Emeralds You will need to look around, but there are some nice alternatives to Emeralds. I think they are more suitable for jewelry applications and actually worth what you pay for them. Sorry, it is just my opinion, but I very seldom see an Emerald from any where that I think is really worth the money.
Tsavorite – A green Garnet from Tanzania. It does not get very large (a 5 carat stone cut is considered very large, 1 carat stones are fairly common in the trade). But it has a refractive index of 1.73 (Emeralds are 1.56) and usually easy enough to find in clean quality rough or cut with NO treatments of any kind. It is harder (7.5) and much more durable than Emeralds (Beryl is a 7.5, but Emeralds are usually so flawed that they really are not this hard). Price wise, it is usually in the same range, sometimes a little more or less… it depends on the market and production. They have the chrome color green and sparkle that Emeralds just do not…
Mint Grossular Garnets – (Merelani Mint Garnet) This is one of my favorites, it is not usually large, but stones that will cut a one carat clean stone are fairly common. Although a lot of this rough is often not clean. It is available and not as dark as a lot of Emeralds, but very pretty… Refractive index of 1.73 or so, it can vary a little bit, it has a lot of sparkle… 7.5 hardness. NO treatments of any kind.
Chrome Tourmaline – It is harder, more durable (7.5), and easy to find either cut or rough and usually less money than Tsavorite and Emerald. Has a refractive index of 1.62 (Tourmaline). It can be too saturated in color if you are not careful when buying the rough. NO treatments of any kind.
Other Tourmaline – while not exactly the chrome color of Emeralds, I have seen a fair amount of material, especially from Afghanistan that is very close or better color than Emerald (in my opinion), gorgeous and price wise pretty reasonable when compared to Emeralds. Usually NO treatments of any kind.
Chrome Diopside – It is a bit softer than Emeralds 5-6 hardness, refractive index of 1.67-1.72,. It can be a little dark in larger stones. It is not hard enough for some jewelry applications like rings, it is fine for earrings and pendants… It is pretty inexpensive and easy to get in smaller sizes usually (1 to 2 gram material). NO treatments of any kind.
Peridot – I know what the average person thinks, but I have seen some material that is Emerald color and with a sparkle (1.68 refractive index and a very high dispersion) that no Emerald could hope to ever match. This kind of Peridot is not common, but I have seen and cut it.. NO treatments of any kind
In conclusion, if you want to buy an Emerald, I wish you good luck.
Just be aware of what is going on, especially in the clarity and grading of Emeralds. Education is your best defense, I hope I educated (scared) you a little bit and maybe told you something from a different point of view.