In a ruby, you will find the mineral corundum, which is scientifically known as the crystalline form of aluminium oxide. Corundum is a rock-forming mineral that forms in a close-packed hexagonal structure. It consists of two aluminium atoms and three oxygen atoms, represented by the chemical formula Al2O3.
While corundum is the main component of rubies, it can also be found in other gemstones such as sapphires. What sets rubies apart is the presence of trace elements that give them their vibrant red color. These trace elements can include iron, titanium, vanadium, and chromium.
Iron is one of the most common trace elements found in rubies, and its presence can affect the intensity and shade of the red color. Higher levels of iron can result in a deeper red hue, while lower levels can lead to a pinkish or purplish tint.
Titanium is another trace element commonly found in rubies, and it can enhance the color saturation and brilliance of the gemstone. It is often responsible for the desirable “pigeon blood red” color that is highly sought after in rubies.
Vanadium is a trace element that can also contribute to the color of rubies. It can produce a range of shades, including red, orange, and purple. The combination of vanadium and chromium can create a unique color known as “padparadscha,” which is a delicate pink-orange hue.
Chromium is perhaps the most crucial trace element in determining the color of rubies. It is responsible for the iconic deep red color that is associated with these gemstones. The presence of chromium gives rubies their rich and vibrant appearance.
In addition to these trace elements, rubies may also contain other impurities such as rutile (titanium dioxide) and spinel (magnesium aluminum oxide). These impurities can affect the gemstone's clarity and overall appearance.
As a sommelier and brewer, I can draw a parallel between the complexity of rubies and the intricate flavors and aromas found in wines and beers. Just as the combination of different grape varieties, fermentation processes, and aging techniques can result in a wide range of flavors, the presence of various trace elements in rubies creates a diverse spectrum of colors and visual characteristics.
The composition of a ruby goes beyond its chemical structure. It is the presence and interaction of these trace elements that give each ruby its unique and captivating beauty. Whether it's the deep red hues enhanced by chromium or the delicate shades influenced by vanadium and titanium, the allure of rubies lies in their natural variations and the stories they tell through their colors.