This ruby resource has been put together by QP Jewellers to provide users with a comprehensive guide to this beautiful, enigmatic gemstone. Our Ruby Range contains some of the most beautiful and affordable ruby jewellery around, so we decided to research thousands of questions people had about rubies so that we could answer all of them with this guide. If you’d like to know what rubies are made of, the cuts and value of ruby jewellery, and the ruby’s cultural and spiritual significance then you’ve come to the right place.Contents:
- The Mineralogy of Rubies
- The Chemistry of Rubies and Sapphires
- How Are Rubies Formed?
- Which Countries Produce Rubies?
- Star Rubies
- Artificial Rubies
- Composite Rubies
- Heated Rubies
- Mining Rubies
- Finding Rubies
- Extracting Rubies
- The Rarity of Rubies
- How Rare are Rubies
- Why are Rubies so Rare
- Rubies around the World
The Mineralogy of RubiesImage source: Géry Parent © (Licence)
The mineralogy of rubies is concerned with the chemical make-up of rubies. It looks at the elements involved in its crystalline structure, red hues and its beautifully-rich lustre. Rubies are made from the same mineral as sapphires: corundum. Ruby is a type of corundum, which is an aluminium oxide compound found in the earth. The difference between the two gemstones is in their colour, which is caused by the different trace elements. The presence of chromium in rubies is what makes them red. The presence and various combinations of other elements such as iron, copper, titanium and magnesium make up the variegated colours of sapphires.
What are rubies and sapphires chemically known as?
The chemical name for corundum is Aluminium Oxide (its chemical symbol is Al2O3).The chemical difference with rubies is that they are made from α-alumina, which is the most stable form of Al2O3. α-alumina is Al2O3 but a small number of the aluminium ions are replaced with chromium ions. These chromium ions form a strong bond with the Al2O3 producing a very stable compound. This is why ruby is the second strongest natural substance. Diamonds are the strongest.
How are rubies formed?
The formation of rubies in the earth is a bit of a mystery for geologists, and there are many reasons why:
- Rubies and sapphires are a type of corundum where chromium (ruby) or iron, titanium and several other elements (sapphires) are present.
- When chromium, titanium, and trace amounts of iron etc. aren’t present in corundum we find the unattractive emery.
- Additionally, if there is too much iron or silica present in corundum then the corundum will form neither rubies nor sapphires.
- But iron and silica are very common, meaning that there’d be very little chance of rubies or sapphires forming. But they have formed. There have been many rubies and sapphires found over the years.
- The best answer proffered by geologists is that the collision of tectonic plates can push limestone deposits down and the heat can convert (metamorphose) the limestone into marble. Simultaneously, molten volcanic granite boiled and bubbled through the marble, removing all of the silica and leaving behind aluminium.
- There is something amiss, however, as these large patches of limestone aren’t always found connected to a source of rubies and sapphires, which we find in sporadic patches throughout the globe. It’s a bit of a mystery.
- As you can see, a very specific chain of events must have occurred for rubies and sapphires to be created. And jewellers across the globe are thankful for it, and the mystery sort of adds to the ruby’s intrigue.
Which Countries Produce Rubies?
Rubies have been found in almost every continent, but they have historically been mined in:
- Burma (now Myanmar)
- Sri Lanka
- North Carolina
- and Columbia.
Star Rubies are very rare. They are formed by the presence of a mineral called rutile (titanium dioxide) in rubies, which forms six pins that pack together in tight, parallel needles. Light reflects off each group of pins and forms a straight line. This line appears as if it’s floating on the surface of the stone. These packs of needles cross in the middle, producing a six-rayed star. The angle between each line of the star is 60 degrees and the effect is astounding. It is very rare, and a star ruby will always fetch a pretty penny.
As we’ve said, star rubies are incredibly rare. If you consider that all rubies are very rare and that star rubies are rare in the ruby world then you can begin to fathom just how rare star rubies are. There is no official number to quantify this rarity, however, but perhaps that’s part of the mystery and allure of star rubies and gemstones in general.
Why are rubies sometimes created in a lab?Image source: Géry Parent © (Licence)
As rubies’ hardness and wave-transmitting properties make it a very useful material, scientists needed a way to producing artificial rubies – where the appearance and clarity was less important than the mineral’s useful properties.
There are two main types of ruby synthesis (of which there are many sub-categories):
- One method uses heat (‘melt’) to combine elements together in a crystalline form. The most popular ‘melt’ techniques are Verneuil's flame fusion and Czochralski's crystal pulling.
- The other uses a solution to dissolve the elements and evaporation to produce the crystalline product once the liquid has been removed. The most common solution techniques are the hydrothermal growth and lux growth methods.
The resulting synthetic rubies can look good enough to use as gemstones—and many are—but most (around 75%) are used for their unique physical properties. Synthetic rubies are used as the bearing material in watches (because they are harder than steel) and as in lasers (as their wave-transmitting properties are unique and very useful).
Composite Rubies – what are they and how are they created?
Composite rubies are rubies that have been put through a process where the impurities are removed from low quality rubies/corundum. The spaces are then replaced by red-tinted lead-glass—a substance chosen because it has almost the same refractive index (R.I.) as rubies.
The R.I. of a substance is how light moves through it. Often, when gemologists check a gemstone, they check its R.I. This is how a composite ruby can sometimes fool an expert. But a composite ruby is nowhere near as valuable as a natural ruby, or even a synthetic ruby. Not only is it not one-hundred-percent ruby, but it is more vulnerable that real rubies as lead-glass is weaker than normal glass, both to physical damage and corrosive chemicals. But, as the lead-glass has almost the same R.I. as rubies, no one can deny the crisp, bright finish it creates. Just be careful not to damage this vulnerable composite stone: the ruby is the hardest substance next to diamonds, but the lead-glass is very weak.
Heated rubies are rubies that have been heated to improve their clarity. Heat treatment is considered to be a natural way of enhancing the clarity and aesthetic beauty of the stone. Most affordable rubies have been heated. They are heated almost to their melting point, which causes the aluminium oxide, the majority of compound that they are comprised of, to change and reform slightly. This changes the structure of the crystals in the ruby, allowing the reddening chromium in the ruby to combine and with different atoms, producing brighter, clearer red hues. There is nothing unnatural about applying heat to minerals, as this is often what they are subjected to deep in the earth. And, as the end result is simply a better-looking ruby, heat treatment is very common—more common, in fact, than not heating a ruby. Unheated rubies of particularly good clarity, colour and quality are much more valuable than heated rubies, mainly due to their rarity.
Rubies are found in mineral deposits. Often a way of finding deposits of rubies (and other minerals and precious metals) is to search the rivers and streams. As rivers erode through rocks, they often break away minerals and metals. Finding fragments of gold or rubies in a river may mean that a deposit exists further up the river. They are also often found in alluvial deposits, in other mineral deposits, such as gold and tin.
One method of extracting the ruby from the surrounding rock (which is often corundum) is to apply diluted hydrochloric acid. If this doesn’t work, use concentrated acid—taking all of the necessary precautions. You may still need to pick away the surplus rock afterwards. Make sure that the red mineral in your rock is ruby, however, as the acid will destroy most other types of gemstone.
The Rarity of Rubies
It is impossible to know how many rubies there are in the world. There is a finite supply, though there are still many active mines throughout the world. We have no way to know how many rubies have been mined so far. Experts may like to hazard a guess, but that’s exactly what you’ll get from them: a guess.
How Rare Are Rubies?
The quick answer is very rare, but so are all gemstones. In fact, the percentage of the Earth’s crust considered to be ‘gemstone’ makes up only a fraction of 1% of the earth’s mass. Then, within that fraction, you find corundum and all of its varieties, of which ruby is the rarest. Within the gem world the ruby is one of the rarest. This fact, combined with the gemstone’s exquisite beauty is the reason why rubies are so valuable.
Why are rubies so rare?
Rubies are so rare because they require a very specific set of conditions to form. The details of these conditions are specified in the How are rubies formed section above.
Rubies Around the World
As mentioned above rubies are found in countries all over the world, with the biggest and highest quality rubies currently coming from Myanmar (previously known as Burma). What follows is a list of the local mines and ruby hotspots throughout the world.
- Rubies in Australia – Rubies are found in several parts of Australia, such as the drainage basin of the Barrington Volcano, the Macquarie and Cudgegong Rivers and parts of the New England area. Australia is a treasure-trove of gemstone and precious metals and some wonderful rubies have been found there.
- Rubies in India – The Karur region of southern India is perhaps the most well-known place for rubies in the sub-continent, but there are many other places throughout this huge, diverse country that are rich with rubies and other precious gemstones and metals. As well as the Karur-Kangayam belt, the Hole-Narsipur belt has a considerable quantity of rubies under its surface. You can also find a lot of quality rubies in Subramaniam in Karnataka.
- Rubies in Canada – There have been no gemstone-quality rubies discovered in Canada yet. Although substantial ruby deposits have been discovered in Greenland. And, as the geology of Greenland and Baffin Island is similar, it is predicted that there will be rich ruby deposits dotted about its terrain.
- Rubies in the United States – Rubies aren’t as numerous as gold in the US, but several deposits have been discovered in North Carolina, South Carolina, Montana and Wyoming.
- Rubies in Africa – Although several ruby deposits can be found throughout the massive continent, Tanzania has a notably rich supply of rubies, of which there are four main ruby-rich areas: Morogoro, Umba, Lossongoi and Longido.
- Rubies in Myanmar – For many centuries, the world’s highest-quality rubies have been mined in Myanmar, in the The Mogok Valley. The best rubies from Myanmar were called pigeon’s blood rubies (for obvious reasons), although the supply of exquisite rubies has dried up in recent years. Over the centuries some of the most expensive and famous rubies have come from Myanmar. However, the US issued an embargo because of the turbulent political and military activity in the country in recent years, and there was evidence of slave labour in the ruby mines. There is also evidence that the profits from the rubies had been funding the Burmese military junta. From 2011-2012 however, there has been a change in the country’s politics—for the better. Perhaps, in time, the nation will stabilise and the world will enjoy their beautiful rubies again.