Ruby – the red king of gemstones
The ruby, known as the “king of gemstones” in ancient Sanskrit, is distinguished by its red color. It is the most valuable of the corundums, followed by the blue sapphire and padparadscha.
The ruby's color is a matter of dispute: what is ruby red?
Like the sapphire, the ruby is a corundum. Except for its red color, it has all the properties of a sapphire. The transition to the pink sapphire is fluid: whether a stone is still “ruby red” or already “sapphire hot pink” is often in the eye of the beholder. Despite the use of color charts, it may happen that one and the same stone is classified as a ruby by one expert and as a pink sapphire by another.
There is not just one shade of red that makes a ruby a ruby. It can have light red tones that already tend towards orange or pink. Or dark, brownish tones.
The color once caused a legendary dispute. The jeweler Louis Cartier argued with the Maharaja of Nawangar about which shade of red was the best. The maharaja insisted that the best rubies had a purple tinge. Cartier, on the other hand, believed that a pure red was the best color for a ruby. In the end, Cartier emerged as the winner of the dispute, and since then, a vivid red (comparable to the red of a traffic light) has been considered the best color for a ruby.
The impact of color on price
Certain color classifications affect the price. Deep red rubies, also known as “pigeon blood” rubies, are particularly popular – and valuable.
The red color of the ruby comes from the element chromium. In addition to their color, rubies also get their fluorescence from it, which makes them glow like a fire from within. The fluorescence is revealed by UV light, which is why it can be admired especially in sunlight.
Use: rubies for jewelry and lasers
Rubies are particularly suitable for jewelry due to their hardness and fluorescent beauty.
However, they are also used in other ways: the red fluorescence of rubies helped to build the first functioning laser in 1960. Rubies – both natural and, primarily, synthetic ones – are still used to make lasers, watches and medical instruments.
Give the gift of jewelry with rubies
Rubies bought loose can be made into a wide variety of jewelry and given as gifts. The king of gemstones is also an eye-catcher as a ring, which particularly attracts attention due to its red sparkle.
If you want to give your beloved a gemstone for their birthday but can't decide on one, you can take advantage of the symbolism of birthstones. According to the American Gem Society, rubies are the ideal stone for those born in July.
Origin & mining sites of rubies
The most valuable rubies come from the Burmese Mogok Valley. These are famous for their blood-red color with violet hues and are also called “pigeon blood rubies”. In addition to their intense color, these stones glow in UV light.
Another mining site in Myanmar is located in the Mong Hsu region. For most of the rubies mined here, the color saturation is improved by heat treatment.
In Winza, Tanzania, rubies of sometimes very good quality were found. However, the finds dried up as early as 2009 – two years after the first stones were discovered there.
The world's largest production of high-quality rubies takes place in Mozambique.
There are also smaller deposits, for example in Madagascar, Sri Lanka and Thailand.
How are rubies mined?
In Mozambique, ruby is mined using modern methods by the company Gemfields. In other countries, this precious stone is mined by local miners using traditional methods. In Sri Lanka, large-scale commercial mining has been banned in order to preserve jobs.
Hardness and inclusions of rubies
Rubies have a hardness of 9 on the Mohs scale. The only natural gemstone that is harder is the diamond. This makes rubies particularly resistant to scratches and signs of wear, so they can be worn as rings without hesitation.
As with all corundums, inclusions are also very common in rubies. These are usually fine rutile needles, calcite crystals, dolomite crystals, pyrite crystals, zikon, pargasite, but also healing cracks, negative crystals, and polysynthetic twins.
An accumulation of the finest rutile needles is referred to in the jargon as “silk”. Even if inclusions have a devaluing effect, a small number of rutile needles prove the authenticity of the ruby. They are also a sign that the stone has not been heat-treated.
Most common cuts
How a ruby is cut depends heavily on the rough stone used. The gemstone cutter tries to emphasize certain advantages of the rough stone, for example, special light reflections or a high-quality color.
Most rubies are oval cut, but other cuts are also possible.
A well-executed brilliant cut can increase the value of a ruby, but only if the ruby's brilliance is good enough for a round cut.
You can also find rubies with an emerald cut, but rarely in stones over 1.5 carats.