Ruby - Information and Ruby Jewellery Buyers Guide

Ruby cut gemstones



Ruby gems, known for their vibrant red colour, have been treasured for centuries for their beauty and rarity. Let us take you on a journey to discover the fascinating characteristics and history of these precious stones.  

The finest rubies come from Burma, although they are also found in many places around the world including Cambodia, India, Madagascar, Australia, USA and Thailand.

Ruby gems have been desired and coveted dating back to ancient civilizations. In many cultures, rubies were believed to possess mystical powers and were associated with love, passion, and protection. Warriors wore rubies into battle, believing that the gemstones would grant them strength and invincibility.

Throughout history, rubies have adorned the crowns and jewelry of royalty and nobility. They have been treasured as symbols of power, wealth, and prestige. Today, ruby gems continue to captivate with their colour and beauty.

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The Formation of Natural Ruby:

Rubies are formed over millions of years in the earth by pressure and heat in areas rich in aluminium.  Rubies are formed from corundum (aluminium oxide), Al₂O₃ for the scientifically inclined

Rubies take on a red colour due to the presence of minute amounts of chromium, when they are formed.  Did you know - rubies come in many other colours, but we call these sapphires.  Ruby and sapphire are the same aside from the trace elements which cause the specific colours.  There is often debate over when a gem goes from being a pink sapphire to a ruby - it's all in the colour.


Rubies in Jewellery

Rubies are second only to diamonds in hardness so make an excellent choice for jewellery which will be worn regularly such as engagement rings.  Rubies are very resistant to most household chemicals although it is wise to avoid bleaches and harsh abrasives.  Some rubies can be fracture filled and the fillers used are not as tough so may be harmed more easily.  Despite their toughness rubies can still be chipped, so it is best to remove your jewellery if you are undertaking rough manual work.


Ruby Value

Colour has the greatest effect on ruby value, an intense crimson red known as pigeon blood is the most desirable.

Clarity is also important.  Most natural rubies have some inclusions with small crystals of other forms and needles (called silks) being most common.  The inclusions are often so small they are nearly impossible to see with the naked eye.  The clearer the stone the more valuable.

Cut - the 'cut' of a ruby in relation to quality depends on a number of factors much like for diamond.  Factors include the proportion, shape, and quality quality of surface polish

Carat - the carat of a ruby is simply it's weight with the unit being a 'carat'.  One carat is 200 milligrams metric weight and for gemmology and jewellery purposes a carat is also divided into 'points'.  One carat = 100 points, so a 20 point ruby is 1/5 carat for example.

If you can measure the ruby then you can use a mathematical formula to estimate its weight, although this is never quite perfect as slight differences in the facets and cut will skew the result.  If the ruby is not mounted in jewellery it can be weighed on specialist scales for a near perfect result.  When set in jewellery carat weights are estimated within the limits of accurate measurement.

Ruby Certification

Rubies can be tested and certified by specialist laboratories, perhaps the best well known being the GIA.  Gems are tested by specialists using advanced tools to certify their quality, their origin (natural or synthetic), and any treatments or enhancements they have received.

These tests are best done on unmounted stones before they are set into jewellery, and a certificate from a respected laboratory will increase the value of the gem.  However such testing is not cheap with prices currently around £120-250 ($150-300) for a comprehensive certification, more for higher carat weight stones.  While worthwhile for higher value pieces for general jewellery it is usually not done as it significantly increases the cost for little benefit to the consumer.

It is important to note that mounted rubies cannot be tested to the same standard and only certain criteria can be checked, results will also be less accurate.  Also note that there are many labs (especially labs in India and China) which provide credit card type certificates with stones.  The value of these certificates is limited and cannot be relied upon for accuracy and they are sometimes more of a marketing exercise than an impartial test.


Ruby Enhancements

Natural rubies are often subjected to 'enhancements'.  These are usually designed to reduce visible flaws, improve the colour or stabilise faults.  Some of these techniques are difficult to detect in the secondary market without advanced (and expensive) tests.  A GIA certification should reveal such treatments but will lead to a significant increase in price for the item.

Common enhancements include:

Heating: Heat treatment of rubies is common and generally seen as acceptable in the gem market.  It is done to enhance the colour and clarity and is a permanent treatment that does not degrade over time nor cause harm to the gem.  Heat treatment can sometimes be detected using a good quality loupe or microscope.  A professional lab should be able to determine if a ruby has had heat treatments.

Fracture Filling:  Technicians use specialist types of glass or silicones to fill in natural fractures and faults within the ruby.  There are a number of techniques and processes used and this type of treatment is generally applied to larger stones.  Fracture filling can often be detected under the microscope, although this may be much harder on mounted gems.

Backings: Some antique rubies set in jewellery would have a metal foil coating applied to the backs to enhance their sparkle, this process is not considered detractive and can be a good confirmation of antique origin and increase the value of the jewellery.


Lab Grown (Synthetic) Rubies

Lab grown corundum (ruby and sapphire) was developed in the late 19th century with Auguste Verneuil being the most influential in making the method commercially viable.  The first retail stones came onto the market around 1905, well over a hundred years ago.

There are two main processes for the production of synthetic corundum, flame fusion and hydro thermal, with the former being the most popular.  Lab grown rubies have the same chemical make up as natural gems and will test as ruby.  Generally they can be distinguished from their natural counterparts by optical analysis under the microscope.

Lab grown rubies allow the buyer to have a larger stone of far superior clarity and colour compared to a natural example at a significantly lower cost.  They are increasingly popular as they do not carry the concern of societal issues in the countries where natural rubies are mined.  They also avoid the need for mining which can have environmental issues, although it should be noted that production does still require significant amounts of energy.


Ruby Simulants

Simulated rubies are not genuine rubies, but alternative gems which have a similar look.  They can be man made or natural, but they will not test as ruby and may have a lower value.

Common natural simulants include:

  • Red Spinel
  • Some Garnets
  • Rubellite Tourmaline

Common man made simulants include

  • Lab grown spinel
  • Lab grown moissanite
  • Garnet doublets
  • High dispersion glass (eg Swarovski Crystal)
  • Cubic Zirconia (CZ)

As long as you understand what you are purchasing there is no problem with buying jewellery with lab grown or simulated rubies at the appropriate price.