HPHT and CVD Diamonds

You’ve probably heard about the HPHT (High Pressure High Temperature) method, but you may not know that it also uses a different method called chemical vapor deposition. Whether you’re wondering about the difference between HPHT and CVD, or you’re interested in knowing more about natural diamonds vs lab grown ones, this article is for you. Learn more about these methods to make an informed decision about your next diamond purchase.

High Pressure High Temperature method

The HPHT method of lab-grown diamonds mimics the formation process of a natural diamond under the Earth’s crust. This method involves building up the pressure to nearly 60,000 atmospheres, which is similar to the conditions a diamond would be exposed to in the earth’s crust. The high pressures and temperatures also help the diamonds grow more evenly, giving them more of a natural look.

A high-pressure, high-temperature process produces a large, gem-quality diamond. This process is known as the HPHT method, and the process involves a laboratory-scale growth cell that contains a tiny seed diamond and a mixture of metals and powders. The growth cell is placed in a chamber that is about the size of a washing machine, where constant temperatures of up to 1,300 degC and more than 50,000 atm of pressure are applied. Once the seed is exposed to the high pressure, carbon precipitates on top of the diamond seed crystal. In just three-and-a-half days, a gem-quality 2.8-carat rough yellow diamond has formed.

HPHT is the most common method of producing diamonds. It mimics the formation of natural diamonds by subjecting carbon to extremely high temperatures. Once the carbon is exposed to these temperatures, it starts to undergo chemical reactions, which forms the diamond. The end result is a diamond with a variety of unique physical properties. Typically, diamonds grown using this process are gray or brown in color, but they are often enhanced by a post-growth treatment.

Chemical Vapor Deposition method

The Chemical Vapor Deposition method is a relatively new method used to grow diamonds in a laboratory. This process consists of applying a gas to a diamond seed, usually hydrogen or methane. The gas mixture is then heated up to several hundred degrees, breaking the molecules and forming a crystalline shell around the diamond seed. Although the process is less energy-intensive than HPHT, diamonds made by CVD are often black or brown in color, and therefore require HPHT treatment to obtain their color. However, over the past decade, CVD technology has been improved and scientists are now able to produce lab grown diamonds in colorless forms without the need for HPHT treatment.

The CVD process starts by exposing a thin diamond seed to high temperatures. The seed is then surrounded by a chamber filled with a carbon-rich gas mixture. As the gas mixture breaks down, ionization takes place and pure carbon bonds with the seed diamond. Once bonded together, the carbon deposits on the diamond seed, forming a larger diamond. This process is described in the article below by Brilliant Earth.

HPHT method

In addition to their beauty, HPHT lab grown diamonds offer many other benefits. HPHT treatment has the unique ability to correct the color of diamonds, whether they are natural or lab grown. A diamond’s color is caused by distortion of the crystal structure, which results in brownish tints. HPHT treatment repositions the crystal structure and permanently lightens these brown hues, creating a diamond with a brilliant and eye-clean color.

The HPHT method is the most common way to create diamonds. This process involves placing a diamond seed in a mechanical press with carbon. The pressure load and high temperature are manipulated in a way that simulates the lattice of a natural diamond seed. The end result is a diamond of exceptional quality. The process is also much more cost-efficient than HPHT, as it requires less sophisticated machinery.

In addition to being identical to natural diamonds, HPHT-grown diamonds are less expensive than their mined counterparts. Natural diamonds have more costs to go through along the supply chain than lab grown diamonds, and the process of mining deposits is expensive. Because there are less steps involved, the HPHT procedure results in a lower cost per carat. This is especially important when considering that diamond prices are expected to continue to decline in the coming years.

Natural diamonds versus lab-grown diamonds

Among the most frequently asked questions when purchasing a diamond engagement ring is “What is the difference between natural and lab-grown diamonds?” These two types of gemstones are almost identical, chemically speaking, and most lab-grown diamonds are certified by the International Gemological Institute (IGI). These reports contain a detailed description of the characteristics of the diamonds, and they follow strict international standards. While the two kinds of diamonds are similar in appearance, there is still a noticeable difference.

Natural diamonds are formed through a process called Chemical Vapor Deposition (CVD). This method involves placing a small seed crystal in a gaseous environment, such as argon, nitrogen, and oxygen, and watching as layers of carbon form around it. In contrast, High Pressure High Temperature (HPHT) diamonds are created by crushing natural graphite under high temperatures. Natural diamonds are formed over billions of years, so the difference is vast.

Natural diamonds are rare and valuable. They were formed in the earth’s crust billions of years ago, and their scarcity is a factor in their value. As a store of wealth for centuries, natural diamonds are considered to be more expensive than lab-grown diamonds. However, some people value the ethical value of lab-grown diamonds above the value they create in their jewelry. The industry is still under fire, however, due to human rights and eco concerns.

Color

HPHT lab-grown diamonds are usually white, but brown and grey diamonds can be produced with the CVD or HPHT process. These variations are caused by structural imperfections. Not all grading institutions grade color the same way, but the IGI is the leading lab-grown diamond grader. It can be confusing to determine what the correct color of an HPHT lab-grown diamond is. In this article, we’ll take a look at some of the differences in color and value.

HPHT synthetic diamonds’ body colors have been evaluated by the GIA since 2007. While early HPHT diamonds were mostly yellow-orange, they now account for a higher percentage of submissions than in the past. However, colorless and near-colorless diamonds have become more popular, with almost half of all HPHT synthetics analyzed by the GIA. This trend will continue as more diamonds from HPHT manufacturing facilities are certified by the GIA.

While Type 1a diamonds contain nitrogen atoms, HPHT synthetics are comprised of mostly type 1b and type IIa. These diamonds are rare and are reserved for royalty, but they are now widely available. HPHT synthetics display many of the same traits as naturally formed diamonds. You’ll find a variety of types in HPHT lab grown diamonds, and each type has distinct advantages and disadvantages.

Physical properties

HPHT lab grown diamonds can have a variety of unique physical properties. While natural diamonds are colourless, they may contain inclusions. Some HPHT diamonds are coloured, including blue and yellow. This is due to the presence of nitrogen and boron, which can cause them to have unusual properties, such as a green tint. HPHT diamonds have the same chemical composition as natural diamonds and the same crystal structure, but without the inclusions.

The internal reflection and whitish graining of HPHT diamonds can cause them to lose their clarity grades. While this type of internal reflection is an optically undesirable characteristic, a high-quality photo will reveal the presence of strain lines. Unlike natural diamonds, which experience varying levels of stress over their long growth history, HPHT synthetic diamonds are grown in a uniform high-pressure environment, so this type of internal reflection does not occur.

In addition to the visual appearance, HPHT diamonds exhibit similar optical properties. Moreover, they both exhibit the same adamantine lustre, high dispersion and brilliance. The two kinds of lab grown diamonds have similar hardness, toughness and stability. Nevertheless, they differ in their impurities and aggregates. For these reasons, diamonds made with HPHT technology are highly desirable for diamond jewelry.

Price

HPHT lab grown diamonds are also known as “lab created diamonds” and are a cost-effective, ethical alternative to mined diamonds. These diamonds are created under controlled laboratory conditions and make up about three percent of the worldwide market. There are several different processes used to grow these diamonds, including HPHT (High Pressure High Temperature) and CVD (Chemical Vaor Deposition). Other processes include ultrasound cavitation and detonation. Their prices vary according to the jewelry setting and the vendor.

HPHT lab grown diamonds have a long, promising future. They are perfectly identical to naturally formed diamonds, yet cost less. The natural process of mining diamonds damages lands, forests, and earth, and is associated with considerable environmental impact. HPHT lab grown diamonds are more environmentally-friendly. They come in a variety of shapes and colors, perfect for engagement rings. And because these diamonds are lab grown, they are characterized by reduced cost and no trace of environmental pollution.

HPHT diamonds can be found in a wide range of shapes and sizes. Their shape is dependent on the method of growth. The diamond seed is generally in the shape of an Octahedron, due to the direction of pressure in the earth’s crust. Lab grown diamond rough has a cuboctahedron shape (HPHT), while CVD diamond rough is a cube.

HPHT and CVD Diamonds