Emerald Treatments and Alternatives
Emerald treatments, such as oiling, are very common. Learn what these techniques do, how emeralds are graded, and what gems make great green alternatives, both colorwise and moneywise.
9 Minute Read
There are many regularly applied emerald treatments and enhancements. I'm going to share my opinions of these practices with you. As consumers, you'll have to decide for yourselves whether you want to purchase treated emeralds.
Common Emerald Treatments
Personally, I don't have any problems with people treating gemstones and selling them in the trade, as long as they disclose the treatments. Nevertheless, some of these emerald treatments are very questionable and I don't recommend them. Of course, others have no issues with them, especially emerald dealers.
Oiling gemstones to fill internal fractures is a common practice. Many different oils are used for emerald fractures. For example, using colorless cedarwood oil is a supposedly acceptable practice. Colored oils are also used.
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This article is also a part of our Emerald Specialist Mini Course, in the unit How to Choose an Emerald.
I have definite issues with oiling gemstones. Although many others in the trade will tell you it's fine, I don't consider this an acceptable practice. I would advise against buying any oiled gemstones.
Why do I say this?
Oil Hides Flaws and Improves Colors
Of course, this is why the treatment is done in the first place. However, these concealed flaws could make the stone more fragile than it appears. It may even be unsuitable for jewelry use.
Dealers Probably Won't Tell You How Much the Stone Was Improved
Why not? Because they can't. Oiling often takes place long before dealers and vendors acquire the stone. Assuming they're honest, they just plain don't know.
You Can't Really Tell the Quality of an Oiled Stone
This is usually to the buyer's loss. Sooner or later, oils will wear off (and out of) emeralds. In other words, the "improvement" isn't permanent. When it wears off, your stone will probably look terrible.
Oiling Can Make Future Repairs Difficult
Keep in mind that emerald jewelry, in particular, suffers a lot of wear and tear. Emeralds usually don't wear well precisely because of their flaws. If you need to fix a crack, chip, or do any recutting, oiling will present problems. The fresh cuts (fixed facets) usually won't match the rest of the stone. In addition, you'll need the stone re-oiled to make it look decent again. This takes time and money. Many cutters (myself included) won't even consider recutting an expensive emerald due to the problems and liability involved.
Consider some alternative gems (see below) instead of buying any oiled stones.
Are Emerald Treatments Like Oiling the Same as Heating Other Gems?
I've heard some dealers compare oiling emeralds to heating sapphires. They argue that both practices are essentially the same. That's not true. Heating sapphires produces basically permanent colors. Furthermore, heating also occurs in nature. Nevertheless, artificial heat treatments — done after mining — should still be disclosed. Have you ever heard of stones coming out of the ground already oiled?
To be clear, when shopping for gems, always assume both emeralds and sapphires receive treatments. However, don't assume the treatments have the same impact on the gems' value and durability.
Opticon is a plastic polymer resin. It's injected onto and into emeralds, both rough and cut, often under a vacuum. Although this treatment has more stability than oiling, it will yellow and disintegrate with age and some solvents. It fills flaws and helps improve color and some durability. (Again, that's why people use it).
If dealers disclose this treatment and lower the emerald price, I'm more neutral on the use of Opticon. However, even after an Opticon treatment, emeralds often still get oiled. I haven't changed my opinion on that.
Disclosing Emerald Treatments
As long as dealers disclose emerald treatments and also value treated stones lower than untreated, quality emeralds, I'm inclined to neutrality.
Do quality, untreated natural emeralds actually exist? That brings us to the next topic to consider.
Do You Want a Flawed but Improved Gem?
The only untreated, natural emeralds I've ever seen that I thought were pretty nice hailed from Zambia. However, I haven't seen a lot of those. Also, keep in mind that Zambian material can (and often does) receive oiling. I should disclose that I probably couldn't afford the ones I did like. To be honest, I didn't want to pay the offered price when I considered what other stones I could buy with the money.
Most all of the natural Colombian material I've seen hasn't been particularly good. It has lots of flaws and inclusions. That's just my experience. You might find some good ones.
Again, emerald treatments exist in the first place to improve these gems. Ask yourself, do you really want a flawed stone that's been "improved?" If so, how much improvement is OK? Where does it stop?
Understanding Emerald Clarity Grades
The GIA Clarity Grading System
The GIA system for clarity grading separates stones into different categories, Types I, II, and III. These categories reflect the likelihood that the stones possess inclusions, based on their geological formation processes. Type I gems usually have no inclusions visible to the naked eye. Type IIs usually possess inclusions, while Type IIIs almost always do. (Emerald belongs in the Type III category).
Although stones can receive the same clarity grades, the grades have different meanings based on the stone category. This GIA model holds that you can't compare all gemstones to each other. We should grade like gemstones to like gemstones.
I don't agree with this grading system.
A Dirty Stone is a Dirty Stone
Sorry, friends — a dirty stone (flawed or included) is a dirty stone. I don't care if they're emeralds and it's accepted practice to call them good quality. Emeralds can get the highest clarity grade, "VVS" (very, very small inclusions), but what that means for Type III gems differs from what that means for Type I gems.
I realize saying "They're really flawed" would impact the sale of emeralds and other gems. However, that's my point. I know emeralds don't occur clean and flawless naturally. What we consider a good emerald, in terms of clarity, will still have inclusions. There's nothing wrong with that. My point is they're included. I don't believe we should have separate clarity categories for emeralds or other stones. They'll still be worth what they're worth because they're emeralds (or whatever) and that's how they occur in nature.
Comparing an Emerald and an Aquamarine with the Same GIA Clarity Grade
In my opinion, having different clarity standards for different gemstones in the GIA system is confusing. That's the main problem.
For example, take an aquamarine (also a member of the beryl family, like emerald). Say you find it has a clarity grade of "VS" (very small inclusions) and it's really quite clean. You probably won't see anything with your naked eye unless you have a lot of training.
Now, let's say you find an emerald also graded "VS." It has the same grade as the aquamarine you just considered. How do they actually compare, in terms of clarity?
It turns out that in the GIA system, aquamarine falls into category Type I. For these gems, a grade of VS means it has minor inclusions, somewhat easy to see with 10X loupe. Emeralds, on the other hand, are Type III gems. For emeralds, a VS score means its inclusions are obvious under 10X. This stone, compared to an aquamarine with the same grade, would actually appear pretty included.
Read the Fine Print
In combination, the GIA categories and grades do describe the stones truthfully. However, as consumers, you'll need to read the fine print and understand the system. Very few people outside of the gem business do. Of course, this information isn't withheld from the public. You can certainly find it. Just do your research.
An Alternative Clarity Grading System
Why not always make clarity grading consistent for all types of stones? For the stones I cut, I use my own common sense gemstone grading system for both clarity and color. It has a set of grades, each with a single meaning, for use on all gems, regardless of "type." Of course, I also have stones graded by GIA gemologists with GIA clarity grades. I work with these at the requests of customers or jewelers with whom I do business.
Gemstone Alternatives to Treated Emeralds
Just to clarify, if you're getting the idea I don't recommend buying emeralds, treated or otherwise, you're correct.
In my opinion, you can buy other, better quality gemstones for the same money. Shop around and you'll find some nice green-colored alternatives better suited for jewelry and actually worth what you'll pay.
Sorry, emerald fans. I very seldom see emeralds from anywhere worth the money.
Personally, I don't like cutting synthetic rough. However, if you really want to have a professional lapidary cut an emerald for you, choose hydrothermally grown synthetic emeralds. Truthfully, they make good replacements, especially when you consider all the dyes, oils, and other emerald treatments the natural gems receive.
I can just hear people saying, "No, give me the dyed, plastic-injected natural gems instead of the lab-grown stuff."
Green garnets from Tanzania, tsavorites don't get very large. The trade would consider a 5-ct cut stone very large, while 1-ct stones are fairly common. However, their color rivals emerald's, and you can usually find them clean, whether rough or cut. Usually, they receive no treatments. Also, these gems can match or exceed emeralds in hardness. Since they typically have few inclusions and no cleavage, they're more durable jewelry stones than emeralds. Pricewise, tsavorites fall in the same range, more or less, as emeralds, depending on the market. However, they also have a dispersion and brilliance emeralds can't match.
Mint Grossular Garnet
Merelani mint garnets are one of my favorites. Typically, you won't find these grossular garnets in large sizes. However, rough that will cut a clean, 1-ct gem is fairly common. Although this mint green isn't as dark as a lot of emerald colors, I think it's very pretty. Some stones can match emerald's hardness and have a lot of sparkle, too. These gems don't usually receive treatments.
Harder and more durable than emerald, chrome tourmaline, rough or cut, is found more easily and for less money than both tsavorite and emerald. If you're buying rough, watch the color. This tourmaline variety can have very intense saturation, which might make for a very dark green gem. Be aware of the difference between chrome tourmalines and verdelites or green tourmalines (see below). Unscrupulous vendors might offer green tourmalines as the more expensive chrome variety.
I've seen a fair amount of green tourmaline material that, while not exactly the chrome color of emeralds, comes very close or better, in my opinion. Material from Afghanistan in particular is gorgeous and very reasonable moneywise when compared to emeralds.
The green chrome variety of diopside has a lower hardness than emerald and a refractive index (RI) of 1.67-1.72. For jewelry applications like rings, it's just not hard enough. However, it should work fine for earrings and pendants. You can find it easily and inexpensively in small sizes (1 to 2 gram material). Be aware that larger stones tend to be darker in color. These gems usually receive no treatments.
I know what most people think. Emeralds and peridots show different shades of green. Nevertheless, I've seen peridots with emerald color and a sparkle (1.69 RI and very high dispersion) that no emerald could ever match. While not common, I've cut this material. These gems usually receive no treatments.
If you still want to buy an emerald, I wish you good luck. However, a little education about emerald treatments and alternatives will also serve you well. Be aware of how the GIA clarity grades work. I hope I've educated (or scared) you a bit. At least, you've now heard from someone with a different point of view.
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