In most contexts, the word 'type' is fairly ambiguous. But in the case of diamonds, the term is used to describe a very specific classification system that looks at these dazzling gemstones on a molecular level. So, put on your scientist caps and read ahead for a comprehensive guide to the different types of diamonds, why you should care about them, and how to make an informed purchase in the future.
What Is a Diamond?
Deriving its name from the Greek word adámas (meaning 'unbreakable'), a diamond is a gemstone that is composed of carbon atoms in a crystal lattice arrangement. Diamonds can form naturally or be grown in a laboratory.
To learn more about the different types of diamonds and their corresponding classification systems and gemology-specific terminology, we turned to industry leader Richard Pesqueira. Ahead, are the ins and outs of this fascinating (albeit sometimes technical) topic.
Meet the Expert
Richard Pesqueira is a Gemological Institute of America (GIA) Graduate Gemologist and the institute’s vice president of business development for North America. He is a diamond expert with more than 30 years of experience.
The Diamond Classification System
The easiest way to think about the classification of diamond types on a molecular level is based on the presence or absence of atoms other than carbon in that crystal lattice referenced above. It’s also essential for differentiating between natural, treated, and laboratory-grown diamonds. "Although diamonds are essentially pure carbon, most contain trace amounts of nitrogen and would be classified as Type I," explains Pesqueira. "Diamonds with no detectable nitrogen are classified as Type II." Going a step further, Type I and Type II each have two further separations.
Gemologists distinguish between these different types of diamonds by using "a standard scientific technique called infrared spectroscopy," Pesqueira shares. "There are also some diamond testing instruments available to jewelers that can separate Type I and Type II diamonds, including the GIA iD100 gem screening device."
Here's what to know about diamond types:
Type Ia is the most common in nature. "Here, the nitrogen atoms are arranged in pairs or single nitrogen atoms paired with a vacancy—a missing carbon atom in the crystal lattice," Pesqueira says. "In Type Ib, the nitrogen atoms are isolated in that each single nitrogen atom has adjacent carbon atoms."
As for Type II, the sub-grades are less complex. "Type IIa has a simple crystal lattice containing adjoined carbon atoms with no nitrogen or other detectable elements, whereas Type IIb contains boron atoms, which can often result in a blue color," he adds.
Type IIa natural diamonds are considered to be extremely rare and will typically cost more than Type I natural diamonds.
One of the most famous Type IIa natural diamonds of all time is Elizabeth Taylor’s iconic Krupp Diamond. Purchased by Richard Burton, this Asscher cut white, colorless diamond was a whopping 33.19-carats and purchased at an auction for $307,000 (now valued at upwards of $9,000,000).
Terminology to Know
When buying a diamond, you’ll likely encounter some terminology you’re not familiar with—but that’s no great shakes. While not necessary to know ahead of time, if you thrive on vocabulary, there are a few concepts and terms to brush up on. For starters, "gemologists use the 4Cs and the nomenclature of the GIA grading system to describe diamonds," Pesqueira says. He also suggests familiarizing yourself with the meaning of fluorescence, diamond treatments, origin, and laboratory-grown diamonds.
"Fluorescence is how diamonds react to ultraviolet light, diamond treatments are enhancements to improve a diamond’s color or clarity, origin is where a diamond comes from, and laboratory-grown diamonds...are grown over a period of days or weeks in a laboratory or factory," he explains.
Understanding Diamond Types
Going beyond the Type I and Type II classification, there are a few notable consumer-facing diamond types available on the market that don’t require a degree in gemology to fully comprehend; one of those being shape. "Most diamonds are round; the balance are fancy-shaped, meaning any shape other than round," Pesqueira says. Fancy shapes include princess, oval, cushion, emerald, marquise, and heart. "The diamond-cutter and polisher determine these shapes, often influenced by the shape and condition of the original mined rough diamond."
Another important classification that’s already been touched on is natural versus laboratory-grown. As you know, natural diamonds form deep within the earth under extreme conditions like high temperature and pressure. "That formation occurred millions or even billions of years ago, and the diamonds reached the earth’s surface through volcanic activity," Pesqueira explains.
On the other hand, laboratory-grown diamonds are grown over a period of days or weeks in a laboratory or factory. "Laboratory-grown diamonds have essentially the same chemical, physical, and optical properties as natural diamonds and the two cannot be distinguished with the unaided eye," he says. "However, because of the vastly different conditions under which they form, GIA experts using specialized instrumentation can differentiate them with 100 percent certainty."
Another type of diamond Pesqueira calls out is fancy-colored diamonds. "These are any natural diamond with a color—often yellow or brown, but including blue, red, green, and others outside of the range of the GIA D-to-Z color-grading scale," he says. These fancy colors are a result of trace elements or the specific geological conditions with which the crystal formed. "For example, fancy blue color is caused by the presence of boron, and fancy green color is the result of exposure to a specific type of radiation."
As with most other categories, rarity often translates to greater value. Because of this, Type IIa natural diamonds (which are considered extremely rare) are going to command a high price. It is worth noting that most natural diamonds are Type I, with traces of nitrogen. However, lab-grown diamonds that are colorless to near-colorless are Type IIa with no traces of nitrogen. As you can see, being able to accurately determine the difference between a Type IIa natural diamond and a Type IIa lab-grown diamond is of the utmost significance because one accounts for approximately one to two percent of all natural diamonds while the other is able to be grown in a laboratory.
How to Choose the Best Diamond For You
Generally speaking, diamond types don’t affect the gemstone’s appearance so unless you’re a rare gem collector, this may not be the most important quality in a diamond when searching for your own (whereas something like the 4Cs will play a bigger part in the decision process). The largest decision you’ll be making will be between a natural diamond and lab-grown diamond—a choice that has pluses and minuses on both sides and is entirely up to you.