Diamond Heat Properties
Most diamonds mined lack the quality necessary to become gemstones. They’re used for industrial purposes which take advantage of the many unique properties of the stone. In addition to its intense hardness and optic properties, there are other traits, including how diamonds interact with heat.
Thermal conductivity refers to a material’s ability to conduct heat. Those with low conductivity are used for insulating while things with high conductive qualities are used for heat sinks. Diamonds have strong conductivity, far more than steel, copper or aluminum. Synthetic isotopically modified diamonds have higher conductivity still.
One use of this conductivity is as heat sinks. These devices transfer heat away from one item to a coolant or into the air, protecting the object from damage. Diamonds are sometimes used in semiconductor manufacturing for this purpose. In computer manufacturing, this can allow for especially high processing speeds without harming circuitry or other wares.
These properties can be used to distinguish diamonds from similar looking stones. A copper tipped probe known as a thermistor applies heat to the stone. Another thermistor measures the temperature of the first to determine if the gem has the thermal conductivity of a diamond. Some older probes however, may have trouble distinguishing a diamond from moissanite.
Diamonds and Electricity
Some gemstones have electrical qualities. One gem species develops an electric charge when heated, attracting dust and other debris. Another gains an electric charge under pressure and is used for radios, tablet and other devices. Diamond’s electrical properties change depending on its trace elements.
Most diamonds are electrical insulators, with strong resistivity, or difficulty electrical currents have flowing through the stone. Depending on individual crystal structure, diamond’s resistivity can be measured at ten to the eleventh power, or as high as ten to the eighteenth power. Its insulating qualities are attributed to the tightly bonded nature of its atoms.
A small percentage of diamonds contain traces of boron among their carbon. This added element transforms diamonds from an insulator to a semiconductor. Such items have many applications including diodes, transistors and integrated circuits. Scientists have experimented with diamond transistors since at least 1991.
Other tests have been conducted with laboratory made diamonds containing trace boron. One experiment published in “Nature” in 2004 described how these diamonds became superconductors, with zero electrical resistance. The diamonds used were polycrystalline aggregates of smaller stones. The diamonds had metallic luster and other metal-like properties when at room temperature, but had different conduction.
Diamond Tools
Diamonds are made of tightly bonded carbon. This close connection gives diamonds their unique refraction, contributing to their brilliance. The physical qualities that make diamonds attractive have other applications. In addition to their role as gemstones, diamonds are used as tools.
The stone’s structure gives it hardness unparalleled in other natural materials. Only a diamond can scratch another diamond. They have strong thermal conductivity, making it a heat sink. Diamonds are able to withstand pressures hundreds of times greater than earth’s atmosphere.
One of the applications of diamonds is as an abrasive. While other materials are capable of polishing or sanding other items, diamond’s hardness allows it to process a greater variety of items. The stone is used in applications as diverse as dentistry and gem cutting. Sometimes it is imbedded into a drill tip. Other uses may involve affixing diamond grit to a wheel, belt or other device.
Diamond knives were invented in 1955 by scientist Humberto Fernández Morán. They’re made by placing a diamond in a metal shaft and polishing the stone to the desired angle. The result is a blade with keen sharpness with a long-lasting edge and few flaws. Diamond blades are ideal for cutting very thin samples for viewing under transmission electron microscopes. When used in conjunction with another type of microscope, diamond blades are used for eye surgery.
Diamond anvil cells are used for high pressure experiments. Two diamonds are purposed for each cell, with their culets, or bottommost facets, facing one another. The material to be examined is placed between these facets. Pressure may be applied via hydraulics, screws, levers or other means. The diamonds that make up these anvils must be of high quality and perfectly aligned for even pressure application. Typical stones have sixteen facets and weigh between one eighth to a third of a carat.
Fire Cutting Techniques
Brilliance, or white light which reflects from a diamond’s table, is a celebrated aspect of diamond cut. It illuminates the stone and draws out many of the light properties of diamond. Fire, or colored light reflected through a diamond’s table, receives less attention but is another major component of diamond cut. Just as diamond cutters strive to find ways to improve brilliance, they seek to enhance fire.
When white light enters a diamond, it doesn’t always stay intact. Depending on the angle at which light hits the diamond, the jewel acts as a prism, separating white light into the colors of the rainbow. The angle of the facets within the stone also contribute to fire. The shallower the angle, the more colored light spreads and the greater the fire.
Another way to promote fire in a diamond is through facet junctions, the corners where facets meet one another. As white light separates into different colors, the hues spread. When these lights hit a facet junction, they reflect back into the jewel’s interior while further separating from each other. This helps fire from turning back into white light.
The more prismatic light spreads apart, the less likely they’ll reunite when exiting the jewel. Colored light which recombines when leaving the diamond translates into added brilliance. Some cutters may add extra facets to the crown, or upper part of the diamond to encourage the spread of colored light. These diamonds may have additional fire.
Other attempts to promote fire in diamonds borrow technology from other fields. One approach uses microlithography, a technique commonly used in making integrated circuits. Etching extremely fine lines over parts of the diamond encourages greater diffraction, which in turn leads to increased fire. The result is especially dramatic under spot lighting.
