Emeralds can range from less than $1 a carat to $100,000 a carat. Any gem has a wide range of quality, from opaque and only suitable for carving to transparent, well-colored and making auction houses grin.
When discussing the transparent, beautifully green emeralds most people imagine, there are emeralds that cost less than $100. They will be less than half a carat in weight, and not as richly colored as other examples of better quality. We have sold emeralds around a carat for under $200, however let’s compare it to another emerald from the same location and size priced at $1,212:
E1452 | medium
Emerald ID: E1452 – Weight: 1.01 Carats – Origin: Zambia Price: $151.50
E167 | medium
Emerald ID: E167 – Weight: 1.01 Carats – Origin: Zambia Price: $1,212.00
E167 on the right is brighter with better green coloration overall, inclusions not placed directly in the center of the stone. Price notwithstanding, it will be the emerald of choice for most buyers.
The 4Cs as applied to emeralds puts color first like any gemstone that is not a diamond. In the case of emeralds, clarity is not as important as much as the arrangement of inclusions in the emerald. Most emeralds are highly included, so this is the norm for them. Of course, this means any emerald that shows high clarity will steeply increase in price. The precise clarity and arrangement of inclusions is usually controlled with the cut by the cutter . The last C with carat weight gauges the rarity of all the other factors put together for the size of the emerald.
One factor that is very important for emerald price and infrequently discussed are common treatments. The vast majority of emeralds, around 99%, are treated for clarity enhancement through oil or resin fillers. This is because they are a Type III gemstone, which means they are almost always heavily included. It is a rare treat to see untreated emeralds like that in the gem industry as a whole, especially big ones over a few carats.
Even in the auction houses, most of the emeralds they show will be treated. One of the most famous exceptions is the Rockefeller Emerald, which has near-perfect transparency with no enhancements. It is exceptional for a huge, 18 carat stone and sold for approximately $5.5 million USD.
Even for untreated emeralds of no fame and inclusions, they still command premiums. Emeralds that are more eye-clean are typically not the most vivid greens either, but there are plenty of exceptions.
Emerald ID: E1452 – Weight: 1.01 Carats – Origin: Zambia – Price: $151.50
E1404 | medium
Emerald ID: E1404 – Weight: 1.09 Carats – Origin: Zambia – Price: $654
Note how expensive E1404 on the right is versus E1452 on the left despite the severe difference in visible clarity? Without the clarity enhancement, E1452 would be even more visibly included. Untreated emeralds that look like their oiled counterparts or slightly more included can command incredible prices of ten to hundreds of thousands of dollars, even in smaller carat weights.
For all the other emeralds in the world that are visibly included, the fractures are filled with either oil or resin. Specific types of oil are a popular choice to oil emeralds, though need to periodically re-oiled. Resin-filled emeralds do not dry out as quickly, but their residue can never be completely removed. This makes oiling the most popular treatment for emeralds.
Because this treatment is so widespread, it also means that emeralds cannot go through sonic jewelry cleaners. The oil is removed and/or damaged, leaving the emerald without its make-up. The numerous inclusions were noted by the French specifically as a “Jardin”, or garden in English.
Where the emerald comes from has an impact on their value, namely in a form of brand recognition. This is because 90% of emeralds in the world come from Colombia, this location is also the one that usually provides the best quality of emeralds too. Zambia is a more recent source that supplies the remaining 10% of gem-quality material. There are other sources that put emeralds on the market, but not in notable amounts.
I have recolored one of the emeralds in our inventory, E1554, as an example:
The difference between emeralds and green beryl is intensity of color, with emeralds being more vivid, popular, and expensive. Emeralds are the same mineral species of beryl, colored by chromium (same stuff that makes rubies red). Rarely they are colored by vanadium. Green beryl is typically colored by iron instead of chromium and vanadium, but this chemistry is not distinct. Incidentally, green beryl typically forms fewer inclusions than emeralds. The price distinction between emerald and green beryl is large, though there are plenty of borderline cases that are difficult to discern with certainty.