Why Synthetics and Simulants?
Synthetic jewels form much faster than their natural counterparts, born in days instead of countless millennia. On a molecular level, natural and synthetic stones are the same, and are both used for jewelry and industrial applications. In fact, the advent of synthetics technology has opened worlds of possibilities for scientific instruments.
Simulants may resemble a fancy jewel, but the two have different atomic and chemical structures. A mock gem may be anything from a different stone to plastic or glass creations. These gemstones are most commonly used for fashion jewelry or to serve as replicas for notable jewels. Connoisseurs concerned about the authenticity and provenance of their jewelry may rest assured that U.S. requires vendors to disclose if a stone is real, grown in a laboratory or made by nature.
Just as there is a demand for fine jewels, some people seek imitation gemstones, also known as simulants. These relatively inexpensive pieces may be used for costumes, experimenting with new looks, deterring theft of fine jewels, and more. Sometimes they’re designed to look artificial, other times to serve as a stand in for finer stones.
While some imitation jewels are made from glass or other manmade products, a number of them are natural minerals. Clear quartz may be faceted as is to resemble a diamond, or dyed to mimic a sapphire or other colored stone. Iolite may simulate tanzanite, spinel rubies, and so on. Simulated or real, jewelers by law are explicit about the authenticity of your purchase.
Diamonds are renowned for their hardness and ability to reflect light. They also have the ability to withstand heat to an enormous degree without cracking or melting. The durability of diamonds have long made them ideal for tools and optics, and are now getting attention from the computer world.
Developments in microprocessing are creating chips that handle enormous amounts of data in the blink of an eye. However, the longer computer chips work, the hotter they become. Diamond’s thermal properties allows for processing speeds that would melt silicon hardware. To help make diamond computers an affordable reality, laboratories are exploring how to synthesize industrial diamonds on a budget.
One of the first gemstones ever synthesized was the sapphire. In 1902, chemist Auguste Verneuil used a technique called flame fusion to crystallize powdered aluminum oxide. Though other synthetic gemstone techniques have arisen since then, Verneuil’s process remains the least expensive. With sources of affordable sapphires to work with, scientists had more freedom to use corundum jewels in experiments.
Synthetic corundum found a place in the spotlight in 1960, when a rod of ruby was used in the first working laser, creating a powerful red beam. Ruby lasers are still used today, and the original machine still functions. More recent innovations include titanium enriched sapphire, creating lasers able to use a variety of light’s wavelengths. Synthetic stones makes constructing these machines cheaper and simpler. Rather than sorting through naturally made stones, looking for jewels several carats large with the desired and chemical compositions, corundum can be specially made for the lasers.
Pioneered by scientist Auguste Verneuil, flame fusion synthesizes sapphire, ruby and rutile by moving chemicals through an intense flame and letting the mixtures cool. The starting materials are aluminum oxide for corundum, or a titanium and oxygen blend for rutile. No matter which stone is being manufactured, the powder must have a high level of purity, 99.9995%, for optimal results. Trace amounts of other chemicals may be added, such as chromium, to add color to the final stone.
Flame fused stones start as powders poured into the top section of a Verneuil furnace. A tiny hole in the vessels bottom allows a trickle of material to pass through a flame 2000C or higher, melting the chemicals. The liquid drips onto a rotating platform, eventually forming a crystal known as a boule. As the boule grows, the platform lowers, allowing more space for the emerging gemstone to expand. The crystal is eventually removed from the furnace and allowed to cool. The finished creation may be used in industry or jewelry.
The Czochralski Process
The Czochralski Process, also known as pulling, is named in honor of the Polish scientist Jan Czochralski. He discovered the technique by accident in 1916 when he dipped his pen in melted tin instead of his inkwell. The tin gathered at the tip of the pen nib, forming a perfect crystal. After further experiments, he published his findings in 1918. His epynomous process is used to this day.
Pulling is used to create ingots, semi conductors and synthesize gemstones. To create a jewel, chemicals are melted in a crucible. A rod tipped with a seed crystal is dipped into the mix, before it is pulled out, rotating at the same time. By controlling the temperature of the melt, the speed of the rotation and pulling, crystals of various sizes are created. The finished jewels are cut to size and used in industrial and decorative applications.
Derived from the Latin “fluxus,” meaning “flow,” flux refers to a substance used in metal work to clean, purify, or help with molten objects. Flux growth is a crystal growth process named for the solvent used to clean and dissolve the necessary minerals. This method is ideal for creating stones sensitive to the high temperatures needed for the Verneuil and Czochralski processes.
Rather than depending on tremendous heat, chemicals are placed into a nonreactive crucible and mixed with flux. The crucible is then receives an airtight seal and is warmed to slightly above what’s needed to achieve saturation. As the mixture cools, jewels form. Sometimes seed crystals are used to aid in formation, other times they take shape on their own.
Named after the geological phenomena hydrothermal circulation, the first successful hydrothermal happened in the mid 19th century. Geologist Karl Emil von Schafhäutl wrote a 1845 report detailing his experience creating microscopic quartz crystals in a pressure cooker. Three years later, chemist Robert Bunsen published his experiences using sealed glass tubes, heat and pressure to make various carbonates. More experiments by different scientists followed suit, including methods creating crystals visible to the naked eye, and ways to make quartz in response to a 1940s shortage. Other gemstones made through hydrothermal synthesis include emeralds, alexandrite and rubies.
Today, the most common method of hydrothermal synthesis is the temperature-difference method. Chemicals are dissolved in water until super saturation is achieved. The solution is then placed in a cylindrical pressure vessel called an autoclave. The spot in the autoclave where the crystal grows is cooler than the area where the mixture lies. The temperature difference causes the chemicals to rise to the top and solidify, turning into stones.