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Types of Diamonds

A Guide to the Diamond Grading System

Diamonds are among the most desirable gemstones in the world. They were traded in India as early as the fourth century BC and have since held humanitys fascination with their dazzling appearance. While diamonds are commonly used in engagement rings, and, of course, April birthstone jewelry, they’re one of the rarest types of precious gemstones in the world. According to the Gemological Institute of America (GIA), only 30% of the diamonds mined globally are gem quality, or fit for jewelry; this is one of the many reasons why diamonds are so expensive

A diamond forms when carbon atoms bond together under intense heat and pressure. These conditions cause the atoms to arrange tightly together and create what is called the diamond cubic crystal structure, which gives a diamond its sparkle when it interacts with light. The chemical composition and atomic structure of a diamond determine its properties — such as color, hardness, and brilliance. In this article, we delve into the different types of diamonds and the grading system used to determine their value. We also reveal the most popular diamond shapes and how to ascertain what type of diamond you have. 

What Are the Different Types of Diamonds?

Natural Diamonds

sort diamonds by color and quality
Experts sort diamonds by color and quality before they are cut and polished.

Natural diamonds have a long journey before they reach our jewelry. They formed billions of years ago deep within the earth’s crust, approximately 100 miles beneath its surface. These diamonds were brought to the surface by underground volcanic eruptions that occurred 20–30 million years ago. There, the diamonds are mined and sorted by size, which is measured in carat weight (which we discuss further in the four Cs of diamonds section). On average, miners sort through 200 to 250 tons of rock to produce a single one-carat gem-quality natural diamond. This underscores how rare the biggest diamonds in the world are — and explains why these massive stones are so expensive. 

Once experts finish the sorting process, master cutters take over. These highly trained professionals use their years of experience to plan and execute the optimal cut of a rough diamond. This results in a considerable loss of carat weight — usually about 50%. After the cutting and polishing process is complete, diamond traders purchase the diamond and send it to a grading laboratory such as the GIA or the International Gemological Institute (IGI) for evaluation. Finally, after the grading report is ready, they sell the diamond to jewelers and diamond wholesalers. The Kimberley Process oversees the diamond supply chain to prevent the sale of conflict diamonds, or diamonds that are traded to fund war or anti-government efforts. It has ensured that all mined diamonds since 2003 are certified as conflict-free. After this stage, diamonds will sometimes undergo further cutting and polishing before they’re finally set into magnificent pieces of jewelry. 

Treated Diamonds

treated diamonds
Treatments can be used to enhance both natural and lab-grown diamonds.

Treated diamonds are natural diamonds that are artificially enhanced to reduce the appearance of inclusions or other imperfections. There are two types of diamond clarity treatments: laser drilling and fracture filling. In the former, an expert uses advanced laser technology to drill very small holes into the diamond. Then, they pour a bleaching agent into these holes to eliminate dark inclusions. The latter treatment involves filling the cracks and cavities of a diamond with a substance made of molten lead. Of these treatments, the GIA and IGI issue grading reports only for laser-drilled diamonds since its effects are permanent. The reason why they don’t recognize fracture-filled diamonds is that the filler deteriorates when exposed to heat and chemicals, making this treatment nonpermanent. 

Lab-grown Diamonds

Lab-grown Diamonds
The key difference between lab-grown and natural diamonds is their origin.

Lab-grown diamonds are chemically and visually identical to natural diamonds. The process of making lab-grown diamonds entails replicating the conditions that form natural diamonds, but over a much shorter period of time in a laboratory setting. The two main methods for creating lab-grown diamonds are high pressure high temperature (HPHT) and chemical vapor deposition (CVD). HPHT mimics the natural conditions that cause diamonds to form beneath the earth’s mantle and can take several months to produce a sizable stone. CVD is more energy- and cost-effective. It involves placing a diamond seed in a sealed container and then filling it with a hydrocarbon gas mixture until it grows. This process usually takes weeks instead of months. 

Some people prefer lab-grown diamonds because they’re less expensive than natural diamonds, allowing them to get a larger stone for the same price. Lab-grown diamonds are commonly mistaken for being more eco-friendly than natural diamonds. However, they can have a larger carbon footprint than natural diamonds, depending on the producer’s energy source. While you can only tell the difference between a lab-grown and natural diamond using specialized lab equipment, the former still hasn’t achieved the status of the latter. La Patiala prefers natural diamonds, especially for more sentimental purchases such as engagement rings. 

Natural Fancy Colored Diamonds

Natural Fancy Colored Diamonds
The Graff Peacock Brooch features a rare 20-carat pear-shaped fancy deep blue diamond and other fancy colored diamonds.

Less than 1% of the world’s diamonds are classified as fancy colored. These natural colored diamonds are a rare phenomenon that occurs when trace elements such as nitrogen, boron, and sulfur are trapped inside a diamond’s crystal lattice during the formation process. Each element absorbs a different color of the light spectrum, thereby reflecting a different hue. These diamonds are rarer and more expensive than colorless diamonds with even the highest grades. This explains why the majority of the world’s most expensive diamond rings and most expensive jewelry feature fancy colored diamonds.

What Colors Are Fancy Colored Diamonds?

The most common and affordable fancy color diamonds are yellow, yellow-orange, and brown. More rare colors are pink, red, orange, blue, and green. Yellow fancy colored diamonds receive their hue from nitrogen atoms that absorb blue light. Fancy orange diamonds are far less common than fancy yellow diamonds, even though they both get their color from nitrogen. This is because the arrangement of nitrogen atoms in fancy orange diamonds absorb blue and yellow light, which is a rare occurrence. Pink and red diamonds are separate categories of fancy color diamonds, but they both get their color from a process called plastic deformation. This occurs when extreme pressure compresses their crystal structure, causing them to reflect red light. Fancy red diamonds are the rarest, but fancy pink diamonds can be much larger than red diamonds, which are usually under one carat. Fancy blue diamonds are also extremely covetable. They contain boron atoms, which absorb yellow light and therefore reflect blue. As for fancy green diamonds, their color is a result of the earth’s natural radiation, which pushes carbon atoms outside of the crystal lattice, thereby reflecting green light. 

Where Do Fancy Colored Diamonds Come From? 

Few known sources of pink and blue diamonds exist, making them extremely rare. In 2020, the Argyle diamond in Western Australia — the primary source for pink diamonds — closed because it couldn’t mine enough diamonds to remain profitable. This means that until we discover a new source of pink diamonds, they’ll rise significantly in value. 

The Four Cs of Diamonds

The Four Cs of Diamonds | The Four Types of Diamonds
The four Cs are the global standard for assessing the value of diamonds.

The four Cs are the characteristics of a diamond that determine its appearance and value. They are cut grade, color grade, clarity grade, and carat weight. 

Cut Grade

The cut grade is the quality of the cutting of the diamond rough. This determines how a diamond reflects light, which has a significant impact on its appearance. There are five grades of diamond cuts that range from excellent to poor. 

Color Grade

 

The color grade refers to the lack of color in a diamond. Colorless diamonds are graded from D (the most transparent) to Z (the least transparent). Diamonds with D, E, and F color grades are the highest-quality colorless diamonds because they’re the most transparent and therefore appear the most “white.” The higher the letter grade, the more undesirable color in the stone. We grade fancy colored diamonds using a different scale that instead measures the intensity of their color. 

Clarity Grade

The clarity grade is the absence or presence of inclusions or blemishes in a diamond. Flawless diamonds contain no sign of inclusions or blemishes, even under intense magnification; this category is very rare. Other categories of clarity are broken down into two or three grades. Very, very slightly included (VVS¹ and VVS²) diamonds have great clarity and slight inclusions that are difficult to notice even under intense magnification. Very slightly included (VS¹ and VS²) diamonds have inclusions you can notice easily under intense magnification, but are still not visible to the naked eye. Slightly included (SI¹ and SI²) diamonds have inclusions you’ll likely notice with the naked eye. These sometimes look like spots or flecks of dust in the diamond. Included (I¹, I², and I³) diamonds have visibly noticeable inclusions. We recommend diamonds above VVS². 

Carat weight

The industry measures the size of a diamond in carats. However, the carat weight can differ depending on the diamond cut, which impacts the visual size. The visual size of a diamond depends on the shape, because some shapes are deeper or have larger surface areas, resulting in a smaller or larger appearance. 

The Types of Diamonds: Chemical Impurities

The Types of Diamonds: Chemical Impurities

Diamond types refer to the chemical and physical composition of diamonds. There are four diamond types: type Ia, type IIa, type Ib, and type IIb. 

Type Ia

This is the most common type of diamond. Type Ia diamonds have a yellow tint because the crystal lattice contains clusters of nitrogen in addition to typical carbon content. The reason why these types of diamonds are yellowish is because the nitrogen atoms absorb blue light and therefore reflect a yellow color.

Type IIa

Only 1% of diamonds classify as type IIa diamonds, making them very rare. These diamonds are free of nitrogen and other chemical impurities, so they absorb no light and therefore have a transparent appearance. Type IIa diamonds form under high pressure. Fancy colored type IIa diamonds are typically pink, gray, yellow, brown, light blue, or light green. These are among the most valuable diamonds in the world. 

Type Ib

Type Ib diamonds account for less than 0.1% of natural diamonds, making them extremely rare. These diamonds have nitrogen spread throughout their crystal lattices in the form of single atoms, not clusters. These atoms absorb a lot of blue light and result in gorgeous, highly saturated yellow, brown, or orange diamonds. Canary diamonds are type Ib diamonds.

Type IIb

Type IIb diamonds represent just 0.1% of natural diamonds. They receive their blue or bluish-gray color from the traces of boron they contain. Boron absorbs red light, resulting in a blue or bluish-gray color.

Diamond Shapes

Diamond Shapes | The Four Types of Diamonds
Diamonds come in a wide array of cuts, from classic rounds to fancy shapes. 

The main diamond shapes are round, oval, square, emerald, cushion, Asscher, octagonal, heart, pear, marquise, and trillion cuts. Round brilliant-cut diamonds are the most popular shape because they’re considered timeless and reflect light beautifully, thanks to their symmetrically aligned 57 or 58 facets. Oval-cut diamonds have similar reflective qualities as round brilliant-cut diamonds. Recently, oval engagement rings have been trending because their elongated appearance creates the illusion of a larger diamond. Step-cut diamonds such as emerald- and cushion-cut diamonds have fewer light-reflecting facets than round brilliant- and oval-cut diamonds — making them less sparkly. However, each facet is longer and narrower, which creates a mesmerizing mirror effect. Asscher-cut diamonds are similar to emerald-cut diamonds, but they’re more square-shaped.

How to Tell What Type of Diamond You Have

How to Tell What Type of Diamond You Have
Send your diamond to the IGI for evaluation in order to understand its qualities.

A diamond certificate will have all the information about a diamond. Both the GIA and IGI are globally respected laboratories that grade natural and lab-grown diamonds. If you don’t have a diamond certificate and want to learn more about your diamond’s technical characteristics, you can send it in for grading. IGI grades mounted diamonds in jewelry, but GIA accepts only unmounted gemstones. Your local jeweler might also have equipment for a diamond appraisal. In general, diamonds with a certificate from a top laboratory are worth more than uncertified diamonds because their quality is guaranteed. As such, we recommend purchasing stones with an official grading report.

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