“Dad?” my son said from the back seat of the car. “Are emeralds real?”
Mercifully, there is some context for that question. He’d been over at a friend’s house, and they’d been playing Minecraft. I don’t know much about the game, but apparently “emerald” is one of the construction materials in the game. Which led to the question.
“Yes,” I tell him. “They are.”
“Wow!” he says.
You knew this one, didn’t you?
Yes. Yes I did. But let’s have some fun with it anyway, because I don’t know as much about them as I’d like.
What is an emerald?
Every source I found (which includes mindat.org, minerals.net, and Wikipedia agree that emerald is a variety of beryl. Chemically it’s beryllium aluminum silicate (Be3Al2Si6O18), with a green color that derives from trace amounts of chromium (the mineral that gives us chrome) and (occasionally) vanadium (a silvery grey mineral). Both minerals oxidize in a variety of colors, which explains how a silvery mineral can turn the mineral green. It naturally forms into hexagonal crystals.
The full market value of an emerald is based on four factors: color, clarity, cut, and carat weight.
- Color: To be an emerald, the mineral must have a medium to dark green color (light green stones are classified as “Green Beryl“, which is not considered as valuable), as measured on a scale from 0% (colorless) to 100% (opaque and black) – the finest emeralds rank about 75% on this scale.
- Clarity: All crystals will have some level of flaws, mostly consisting of inclusions (other minerals trapped in the crystal) and cracks. Flawlessly emeralds are stones with no inclusions or fissures visible to the naked eye.
- Cut: This is not a natural property of the stone, but the way it was cut after it was mined. Raw stones are less valuable for the same reason that a tree trunk sells for less per pound than a table of the same wood, but a bad cut can destroy the stone.
- Carat weight. A carat is 0.2 grams (or 0.007055 oz). The value of stones of th same quality does not change in a linear fashion, because larger high-quality stones are rarer than smaller ones. Consulting Singhal Gems International, a good quality 1.0 carat emerald can range from $500 to $1,125, while a good quality 5.0 carat emerald can range from $7,500 to $15,000 in value.
Where are they found?
The largest emerald deposits can be found in Colombia, Brazil, and Zambia. They are mined elsewhere in the world, but those three nations produce most of them. Colombian emeralds are often considered to be the overall finest form of emerald, as they are primarily colored by chromium. Zambian and Brazilian emeralds are more frequently colored by vanadium, with Brazilian emeralds being darker and more heavily included and Zambian emeralds having a bluish-green or grayish-green color.
What is the biggest emerald ever found?
That’s… tricky. What, exactly, do you mean by that question?
The International Gem Society website breaks them down into three categories: named emeralds, unnamed emeralds, and “other large emeralds”. They state that the largest named emerald is the “Emerald Unguentarium”, a 2,860 carat emerald vase currently on display in the Imperial Treasury in Vienna.
The Daily Mail disagrees with this statement, as they report on a watermelon-sized emerald named Teodora, which came in at 57,500 carats. It should be noted, however, that gem experts were skeptical of this claim, and that the owner was arrested on multiple fraud charges. A gem expert who studied it found evidence that it was lower-quality emerald (possibly mixed with white beryl) that had been dyed to make it appear more valuable. Because of this, when it went up for auction, no bids were made.
The largest unnamed emerald is an uncut Colombian crystal in a private collection that weighs 7,052 carats.
“Other large emeralds” is dominated by the Bahia Emerald, which was an 840 pound stone from Bahia, Brazil. The stone “reportedly contains over 180,000 carats of emeralds”, one of which is a single stone that is apparently described as the size of a man’s thigh. There is an ongoing legal battle over ownership of this stone, which shouldn’t surprise anyone since it’s been valued at upwards of $400 million. This stone, unlike Teodora, appears to be genuine.
Genuine, and large.