Technology

Industrial diamond is chosen for performance rather than appearance, and almost all of it is made in factories. The US Geological Survey reports that in 2025 synthetic material made up more than 99% of global industrial diamond production and consumption, and that worldwide output exceeded 15 billion carats. China leads production, followed by the United States and Russia; together they account for about 99% of synthetic output.

The industry began at General Electric, where Tracy Hall achieved a reproducible synthesis on December 16, 1954, in his “belt” press, a high-pressure, high-temperature (HPHT) apparatus that converts graphite to diamond with a molten iron catalyst. GE announced the result in February 1955.

Most industrial diamond is used as an abrasive: grit bonded into grinding wheels, saw segments for concrete and stone, wire saws and polishing powders. Drilling is another major use. GE invented the polycrystalline diamond compact (PDC), a layer of sintered diamond bonded to tungsten carbide, in 1971 and began selling PDC cutters in 1976. A 2015 history by a Baker Hughes engineer in Drilling Contractor, the magazine of the International Association of Drilling Contractors, reported that PDC bits drill more than 90% of worldwide footage in oil and gas wells; a 2010 Sandia National Laboratories report says more cautiously that PDC drag bits dominate oil and gas drilling. Diamond-tipped tools also machine aluminum alloys, composites and ceramics, but they wear quickly on steel because hot iron dissolves carbon.

Diamond combines properties that rarely occur together. High-purity single-crystal diamond conducts heat at more than 2,000 W/m·K at room temperature, roughly five times better than copper, yet it is an electrical insulator with a band gap (the energy needed to free an electron to carry current) of 5.47 eV against 1.12 eV for silicon.

As a heat spreader, a thin diamond plate sits beneath a hot chip and moves heat sideways before it builds up. Gallium nitride (GaN) radio-frequency amplifiers and high-power laser diodes are typical users. Element Six and Japan's Orbray began a wafer-scale single-crystal diamond partnership in June 2024, when Orbray had grown material up to 55 mm across; in June 2026 they reported a reproducible 3-inch substrate process, with 4-inch in development.

As a semiconductor, diamond could in principle handle higher voltages and temperatures than silicon carbide or GaN. Boron doping makes it p-type, but no shallow donor exists: phosphorus sits 0.6 eV below the conduction band against 0.37 eV for boron acceptors, so n-type doping has had limited success, and large low-defect wafers remain hard to grow. Diamond transistors remain at laboratory and pilot scale.

As a window, diamond grown by chemical vapor deposition (CVD) transmits from about 225 nm in the ultraviolet to the far infrared and microwaves, with weak absorption bands between 2.5 and 6.5 µm. It is used in carbon dioxide laser windows, synchrotron X-ray beamlines and high-power microwave systems.

A nitrogen-vacancy (NV) center is a point defect in which a nitrogen atom replaces one carbon atom and sits beside an empty lattice site. In its negatively charged form the defect has a spin triplet ground state: three magnetic sublevels, two of which lie about 2.87 GHz above the third when no field is applied. Green laser light excites the center, and the brightness of its red fluorescence (zero-phonon line at 637 nm) depends on the spin state. A single quantum spin can therefore be read with an optical microscope and microwaves, a technique called optically detected magnetic resonance.

The spin holds its coherence for up to milliseconds at room temperature in very pure diamond, which is unusual among solid-state qubits. Magnetic fields, electric fields, strain and temperature all shift the resonance. NIST reports magnetic field detectivity down to nanotesla per root hertz on length scales of a few tens of nanometers, in air and at room temperature.

In 2015 physicists at Delft University of Technology entangled electron spins in two diamonds 1.3 km apart and performed one of the first loophole-free Bell tests. Hardware has followed the physics: on May 31, 2022 the Pawsey Supercomputing Research Centre in Perth installed a Quantum Brilliance device that it called the world's first room-temperature diamond-based quantum computer located on-site in a supercomputing facility. Quantum-grade diamond is engineered rather than mined, grown by CVD with nitrogen added in controlled amounts.

A diamond anvil cell (DAC) squeezes a sample between the flat tips of two gem-quality diamonds. The anvils usually weigh between 1/8 and 1/3 ct, and their polished tips, called culets, are typically 100–250 µm across. Because a modest force acts on a tiny area, the pressure becomes enormous. A thin metal gasket with a drilled hole holds the sample.

The cell was developed in 1958 at the US National Bureau of Standards (NBS) by Charles Weir, Alvin Van Valkenburg, Ellis Lippincott and E. N. Bunting, and independently at the University of Chicago. Diamond's transparency made the design work: infrared light, visible light and X-rays pass through the anvils, so a sample can be measured while under pressure and heated by laser at the same time.

Gemology supplied the pressure gauge. In 1972 NBS researchers published a method based on the sharp red fluorescence lines of ruby, which shift steadily to longer wavelengths as pressure rises, so a speck of ruby beside the sample acts as a manometer. Cells passed 100 GPa in 1975 and now reach the roughly 360 GPa at Earth's center, while specialized double-stage anvils reported above 600 GPa in 2012, and the same group later reported above 750 GPa in 2015 and beyond 1 TPa in 2016, figures that remain contested. DAC experiments underpin models of planetary interiors and the search for high-pressure phases, from dense ice and nitrogen to superconducting hydrides.

Synthetic sapphire is single-crystal aluminum oxide, chemically the same as natural corundum but grown colorless and in large boules for industry. Manufacturers use melt-growth methods such as Kyropoulos and Czochralski, which cool or pull a large crystal from molten alumina, while the older Verneuil flame-fusion process still supplies small parts and gem rough.

At 9 on the Mohs scale, sapphire resists scratching by almost everything except diamond and a few other superhard materials. Watch crystals (the transparent cover over the dial) are a familiar use: Rolex specifies a scratch-resistant sapphire crystal on the Submariner, and Apple lists a flat sapphire crystal display on the Apple Watch Ultra 3 and a sapphire crystal lens cover on the iPhone 17 Pro cameras. Sapphire phone screens proved harder to scale: GT Advanced Technologies, which had built a sapphire operation to supply Apple, filed for bankruptcy in October 2014.

The largest industrial use is as a substrate, the wafer on which other crystals are grown. In 1986 Isamu Akasaki and Hiroshi Amano grew high-quality gallium nitride on sapphire by first depositing an aluminum nitride buffer layer, and in 1993 Shuji Nakamura produced bright blue GaN-based LEDs. The three shared the 2014 Nobel Prize in Physics. Blue LED chips coated with phosphor produce most white LED light, and a 2016 review reports that sapphire is still the most popular commercial substrate for them. The material also serves as windows for infrared sensors.

On May 16, 1960, Theodore Maiman operated the first laser at Hughes Research Laboratories in Malibu, California, with Irnee D'Haenens and Charles Asawa. Its gain medium was a small rod of synthetic pink ruby, about 1 × 2 cm, with silvered ends and a helical flash lamp around it. Chromium ions (Cr³⁺), the impurity that colors gem ruby, absorbed the flash and emitted coherent red light at 694.3 nm. Hughes announced the result at a press conference on July 7, 1960, and Maiman's paper appeared in Nature on August 6. Other materials soon displaced ruby for most purposes, but ruby fluorescence remains the standard pressure gauge in diamond anvil cells.

Quartz works in almost every electronic device. It is piezoelectric, an effect discovered by Jacques and Pierre Curie in 1880: squeezing the crystal produces a voltage, and a voltage deforms it. A thin quartz plate or tuning fork therefore vibrates at a very stable frequency in a circuit. Warren Marrison built the first quartz clock at Bell Telephone Laboratories in 1927 and an improved frequency standard the next year, published that February by Horton and Marrison in the Proceedings of the IRE. Seiko sold the first quartz wristwatch, the Astron, on December 25, 1969; its crystal ran at 8,192 Hz and kept time to about five seconds a month. Most watches now use 32,768 Hz crystals (2¹⁵ per second), and commercial oscillators use quartz grown hydrothermally rather than mined crystal.

Automation reaches from the recovery plant to the grading bench. At mines, X-ray transmission (XRT) sorters image crushed ore, tell diamond from rock by differences in atomic density, and eject the diamonds with bursts of air. Recovering large stones early reduces the risk that they break in later crushing. Lucara's Karowe mine in Botswana installed TOMRA XRT sorters in 2017 and in August 2024 recovered Motswedi, which TOMRA reports at 2,492 ct as the second-largest diamond on record; Lucara has given 2,488 ct since December 2024.

In rough planning, inclusion-mapping scanners such as Sarine's Galaxy systems build a three-dimensional model of a stone and its flaws. Planning software then proposes polished shapes balancing yield (the weight retained after cutting) against the grades each option achieves.

Grading is the newest target. On July 27, 2020 GIA announced that it had begun grading diamond clarity with an artificial intelligence system built by IBM Research and trained on GIA hardware data and tens of millions of diamonds its graders had examined. GIA's Tom Moses said the goal was consistency, accuracy and speed. The system was in limited use at GIA's New York and Carlsbad laboratories, and GIA said it would extend to more sizes, shapes and qualities. Sarine sells devices and software that grade color, clarity and cut automatically. Such systems apply the rules and training data they were built on, so their results are only as consistent as those references.

A digital twin is a data record of one stone, built from scans, photographs, weight and grading results, sometimes starting at the rough stage so the polished gem can be matched to its source. De Beers introduced its Tracr blockchain platform in 2018 and launched it at scale in 2022. By 2025 it reported more than three million diamonds registered at source, with country-of-origin data for stones over one carat, and requires users to be Responsible Jewellery Council members. A blockchain makes records hard to alter once written but cannot prove the first entry was true, which is why Tracr pairs its ledger with Sarine scanning data. Everledger, an early provenance start-up, entered administration in 2023.

Cryptocurrency reached the top of the market on July 9, 2021, when Sotheby's Hong Kong sold The Key 10138, a 101.38 ct D-color pear-shaped diamond, for US$12.3 million in crypto. Tokenization divides ownership of stored stones into digital units: Diamond Standard issues coins and bars holding certified diamonds, recorded on Hedera. Their value depends on custody, audits and regulation, not the ledger alone.

GIA advises online buyers to check 360° views and return policies. Signet Jewelers bought Blue Nile for US$360 million in 2022; its March 2026 annual report said it would sunset jamesallen.com, and its September 2026 quarterly report records James Allen becoming a collection within the Blue Nile site in May 2026, with $31.3 million of inventory write-downs.