"Natural diamonds formed deep in the earth under extreme pressure and high temperature as long as three billion years ago. Volcanic activity brought them to the surface where they lay in a type of volcanic rock formation known as kimberlite pipes, waiting to be mined. Only about five percent of kimberlite pipes contain enough diamond to make them economically feasible to mine."

"Today, laboratory-grown diamonds are created by two methods, according to Dr. James Shigley, GIA Distinguished Research Fellow, who has been researching laboratory-grown diamonds at GIA for more than 30 years."

"High pressure, high temperature (HPHT) diamonds are produced in a laboratory by mimicking the high pressure, high temperature conditions that form natural diamonds in the Earth. This process produces a distinctively shaped laboratory-grown diamond crystal."

"The chemical vapor deposition (CVD) method involves breaking down the molecules of a carbon-rich gas, such as methane, into carbon and hydrogen atoms, which then are deposited on diamond seeds to produce a square-shaped, tabular diamond crystal."

"Growing diamonds by either method typically requires less than a month for most sizes. Most CVD-grown diamonds require additional treatments like heat or irradiation to enhance or change their colors after the growth process."

"Typically, laboratory-grown diamonds have weighed a carat or less, but as technology and techniques improve, larger stones have appeared in the market."

"Because laboratory-grown diamonds are essentially chemically and optically the same as their natural counterparts, traditional gemological observations and old-style “diamond detectors” are not able to tell them apart. Identification at a professional gemological laboratory or using sophisticated devices developed by GIA and other organizations are the only reliable methods to separate them from natural diamonds."

"Natural diamond crystals (left) typically form in rounded octahedral shapes caused by conditions deep within the earth. They’re brought to the surface by volcanic eruptions that form kimberlite pipes (center)."

"The growth chamber is heated to 1300-1600 °C with pressures above 870,000 pounds per square inch."

"While natural diamond crystals tend to form as octahedrons, HPHT synthetic diamond crystals typically have cubic faces in addition to octahedral ones. Because the shapes of natural and HPHT synthetic diamond crystals are different, their internal growth patterns also differ dramatically. These growth patterns are among the most reliable ways to separate natural from synthetic diamond crystals."

"Most mining for diamonds is expensive because of the tremendous volume of ore that must be removed and then processed."

"In addition, as with most things we purchase, quality and rarity drive price. Low-quality “industrial” diamonds make up the vast majority of rough recovered from most mines. These are unsuitable for use in jewelry."

"Colored diamonds take the question, “Are diamonds rare?” to the extreme. Most of these spectacular beauties are far rarer than diamonds in the GIA D-to-Z color range. Some experts estimate that fancy-color diamonds represent only two percent of total rough diamond production."

"While advertising did not create our desire for diamonds, it certainly helped fuel the demand for diamonds, especially beginning in the 20th century. Advertising copywriter Mary Frances Gerety wrote the famous slogan “A diamond is forever” in 1947, and it has appeared in virtually every De Beers ad since. So compelling was the advertising campaign that the diamond engagement ring quickly became the way to express marital love and commitment. In fact, in 1999 Advertising Age named it the top slogan for the 20th century."

"Advertising has been extremely successful in promoting diamonds not only as a symbol of status and luxury, but also as the perfect symbol for a long and successful marriage. But it’s unlikely that advertising would be effective if it didn’t tap into the already deep connection humans have to the inherent qualities of diamond: durability, timelessness, beauty and rarity."

"A diamond’s value is often affected by the rarity of one or more of the 4Cs. Colorless diamonds are scarce—most diamonds have tints of yellow or brown. So a colorless diamond rates higher on the color grading scale than a diamond that is light yellow. Value and rarity are related: In this case a colorless diamond is more rare and more valuable than one with a slight yellow color. The same relationship between rarity and value exists for clarity, cut, and carat weight."

"The 4Cs describe the individual qualities of a diamond, and the value of an individual diamond is based on these qualities. The terms that people use to discuss the 4Cs have become part of an international language that jewelry professionals can use to describe and evaluate individual diamonds."

"Today, the descriptions of each of the 4Cs are more precise than those applied to almost any other consumer product. And they have a long history. Three of them—color, clarity, and carat weight—were the basis for the first diamond grading system established in India over 2,000 years ago."

"Subtle differences in color can dramatically affect diamond value. Two diamonds of the same clarity, weight, and cut can differ in value based on color alone. Even the slightest hint of color can make a dramatic difference in value."

"Diamonds come in many colors. Diamonds that range from colorless to light yellow and brown fall within the normal color range. Within that range, colorless diamonds are the most rare, so they’re the most valuable. They set the standard for grading and pricing other diamonds in the normal color range."

"Few things in nature are absolutely perfect. This is as true of diamonds as anything else. Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they’re called clarity characteristics. Clarity is the relative absence of inclusions and blemishes."

"With the traditional diamond growth method, called high-pressure, high-temperature (HPHT), synthetic diamonds are produced from carbon material in apparatuses that mimic the high pressure, high temperature conditions of natural diamond formation in the earth."

"The newer method, chemical vapor deposition (CVD), involves filling a vacuum chamber with carbon-containing gas that crystallizes on a synthetic diamond seed. This method uses lower temperatures and pressures than HPHT. Both methods are currently popular methods of diamond growth. The CVD diamond growth method requires a lower upfront equipment cost than HPHT but may require subsequent treatment to improve the color of the diamonds grown."

"HPHT stands for high pressure, high temperature and is one of the primary methods used to grow diamonds in a lab. This diamond growth process subjects carbon to extreme temperatures and pressures and is meant to replicate the extreme heat and pressure conditions deep within the earth where natural diamonds form."

"Diamond seed is placed in a specifically designed press."

"The growth chamber is heated to 1300-1600 °C with pressures above 870,000 pounds per square inch."

"The molten metal dissolves the high purity carbon source."

"Carbon atoms precipitate on a small diamond seed crystal, and a synthetic diamond begins to grow."

"In greater detail, HPHT diamond growth takes place in a small capsule inside an apparatus capable of generating very high pressures. Within the capsule, a carbon starting material, such as graphite, dissolves in a molten flux consisting of metals such as iron (Fe), nickel (Ni) or cobalt (Co), which lowers the temperature and pressure needed for diamond growth. The carbon material then migrates through the flux towards the cooler diamond seed and crystallizes on it to form a synthetic diamond crystal. Crystallization occurs over a period of several days to weeks to grow one or several crystals."

"The industry has seen a significant increase in the quantity, size, and quality of laboratory-grown diamonds, making them viable for commercialization on a larger scale. Nevertheless, there have been relatively few changes in laboratory-grown diamonds during the last five years, indicating that developments have largely stabilized for now. This overview summarizes the two diamond growth processes: high-pressure, high-temperature (HPHT) and chemical vapor deposition (CVD)."

"Although the mechanisms for laboratory growth of diamonds are well established (e.g., Eaton-Magaña and Shigley, 2016; Eaton-Magaña et al., 2017; D’Haenens-Johansson et al., 2022), this article provides a brief summary of the CVD and HPHT growth processes. For both methods, a diamond substrate (often referred to as a “seed” in HPHT growth) is used to create the crystal blueprint from which the new diamond is created. The quality, size, and preparation of the substrate can have a significant impact on the resulting diamond (D’Haenens-Johansson et al., 2022). Substrate availability—previously a limiting factor for commercial production—has dramatically improved to meet demand."

"Both are diamonds, of course. The first is a natural diamond created by forces deep within the young Earth. The second is from a laboratory and possesses essentially the same chemical, physical and optical properties as its natural counterpart."

"Even though synthetic diamonds have the same chemical make-up as natural ones, they have identifying markers caused by their growth conditions that GIA scientists use to tell them apart from natural diamonds. These markers even allow GIA scientists to identify which method had been used to grow the diamond."

"In greater detail, CVD diamond growth takes place inside a vacuum chamber filled with a hydrogen and carbon-containing gas, such as methane. A source of energy — such as a microwave beam — breaks down the gas molecules, and the carbon atoms diffuse towards the colder, flat diamond seed plates. Crystallization occurs over a period of weeks, and several crystals grow at the same time. The exact number depends on the size of the chamber and the number of seed plates. The tabular crystals often develop a rough edge of black graphite that needs to be cut away. They also display a brown color that can be removed by heat treatment prior to faceting. Most CVD-grown colorless material on the market were probably once brown crystals that have been decolorized by HPHT annealing."

"Natural diamonds are the most desired luxury jewellery product, average purchase prices have increased 25%, Gen Z is now the second largest generation buying diamonds, and non-bridal occasions account for three-quarters of overall US demand. These are some of the key findings of De Beers Group’s latest US Diamond Acquisition Study, featuring responses from 18,500 women aged 18 – 74 across the industry’s largest consumer market."