What is Sapphire?
Sapphire gemstones are commonly mined like most other precious gems, however, the commonly used Sapphire crystal is actually artificially manufactured. This artificial Sapphire is an incredibly hard form of optically transparent crystal that looks and behaves like glass or diamond. Unlike glass though, Sapphire cannot be moulded. This material can be grown into shapes such as tubes and rod, then ground and polished if necessary.
The first synthetic Sapphire was created in 1902 by a French chemist called Auguste Verneuil.
What are Sapphires made of?
Since 1902, various methods of making Sapphire have been developed, but generally Sapphires are made using high heat and pressure to turn Aluminium Oxide into a single crystal with no porosity.
Its characteristic blueish colour is due mainly to the presence of small amounts of Iron and Titanium and normally ranges from a very pale blue to deep indigo, although they can be found in a range of hues including yellow, green, pink, purple, and colourless.
Sapphire material properties
It is one of the hardest materials in existence. It is chemically inert and will not melt in contact with acids and alkalis. In addition, it can transmit ultraviolet, visible, and infrared light, as well as microwaves — which is a range broader than most materials.
Synthetically produced Sapphire crystals also have high thermal conductivity, up to 40 times more than glass. With a melting point of over 2000°C, its strength is five times that of glass and due to its purity and transparency it can be used as viewing window in high pressure and vacuum applications.
On the hardness scale, the only material tougher than it is Diamond, in fact, hardness and durability is the main reason for Apple’s interest in Sapphire glass for their iPhones, as it is incredibly scratch resistant. Its fracture toughness is around 4 times greater than that of Gorilla Glass, although any small impurity in the material makes it quite brittle and can severely compromise its structural integrity.
This material continues to be engineers’ material of choice for applications that call for reduced contamination, lower particle generation and increased productivity. In particular, Sapphire tubes are used in various analytical instruments in lamp applications that transmit visible, infrared or ultraviolet light, often with high intensity at high temperatures and pressures.
Most synthetic Sapphire is used in industrial processes, but some particular colours are useful for laser applications. Ruby (Red) Sapphires, for example, are used to create red and new-infrared lasers thanks to their relatively unique capacity to be turned to the appropriate wavelengths, thanks to their Chromium impurities.
Sapphire in Art and Design
This material is widely used in art and design, specifically in jewellery. Another common consumer design application is the creation of extremely hard and scratch-resistant coverings for lenses or high-end watch faces.
When industrial Sapphire was introduced to watchmaking in the 1990s, it was meant to be the least conspicuous part of a watch; a way of showing off the intricacies of openwork or skeletal movements. Now, advances in manufacturing processes have made it possible for watchmakers to use Sapphire crystal as a stand-alone, virtually scratch-proof component; a prominent decorative element, or even as the material that the watch itself is made out of.
The well-known status of this gem, alongside its popularity in jewellery, will see it used in a wide variety of art and design applications for decades to come.