All members of the corundum species share a common chemical composition and crystal structure while trace amounts of different chemical elements are responsible for the various colours of the different varieties. These elements absorb portions of the visible light spectrum producing the different colours we perceive. Ruby owes its dark pinks and rich, vibrant reds to the presence of chromium (Cr) in its structure.
Red corundum is called ruby, blue corundum is known as sapphire and all other colours are considered fancy coloured sapphires and are named for their particular hues for example: pink sapphire, yellow sapphire, green sapphire etc. The most sought after fancy coloured sapphire is the orangey pink variety known as Padparadscha which means ‘lotus flower’ in Sinhalese.
Where can you find the rubies you need?
Pierres de Charmes carries a vast selection of fine quality rubies, sapphires and fancy coloured sapphires. Our collection of well-cut stones includes many different shapes and sizes including calibrated stones.
Ruby Fact Sheet
Ruby and other corundum varieties are amongst the few precious gems that possess all the necessary qualities making them ideal for use in jewellery. All corundum varieties display a bright vitreous lustre, have a hardness of 9 on the Mohs scale, and are extremely resistant and stable. Ruby can also display a six or rarely twelve-rayed star effect.
|3.80 à 4.05|
|Displays strong pleochroism of red and orangey-red.|
Gemmologists can use many instruments to identify ruby. The chromium present in ruby’s structure produces a diagnostic absorption spectrum that can be seen using a small portable instrument called a spectroscope.
With the microscope, gemmologists can use the presence and appearance of certain inclusions including, crystals, needles and healing fissures, to distinguish natural ruby from synthetic ruby.
The most important ruby deposits are found in Myanmar, Tanzania, and Mozambique. Other sources of ruby include Thailand, Vietnam, Sri Lanka, Pakistan and Afghanistan.
Advanced laboratory testing can help determine the geographic origin of some rubies. Certain localities, such as Myanmar, can command a premium on today’s ruby market.
Ruby crystals can be found in metamorphic and alluvial deposits. Rough ruby crystals usually present as short, six-sided, prismatic shapes. However, those found in alluvial deposits that have spent extended periods being transported by rivers may appear as water worn pebbles.
Is ruby treated?
Ruby is routinely heated to improve its colour by eliminating brown or blue nuances. This treatment is permanent and is considered acceptable by the gem-trade.
Some lower quality rubies may contain numerous surface-reaching fractures. These rubies can be treated by filling the fractures with various substances (most commonly lead glass) in order to make the fractures less visible. Rubies treated in this way will have a significantly lower value than an untreated or simply heated ruby of similar appearance. This treatment is not permanent and acids commonly used in jewellery making and cleaning can damage the glass filling. This type of treatment is easily detected by gemmologists and must always be disclosed when selling, as it is not stable. Pierres de Charme does not buy or sell lead glass fracture filled rubies.
Ruby in jewellery
Due to its very durable nature, ruby is well suited for all types of jewellery. Ruby remains one of the most desirable and valuable gems of the world. It is also the birthstone for the month of July.
Value and quality criteria
Colour is the most important quality criteria for ruby. Both ruby and pink sapphire owe their colour to trace amounts of chromium in their structure. Essentially, the colour pink is just a less saturated red so the line separating pink and red is fluid at best and many rubies show slight hints of pink. The most desirable colour for ruby is a vibrant red known as pigeon’s blood. As specific colours are difficult to define this term used for colour designation has been the subject of much debate in the gemstone industry.
A ruby’s clarity will also have an impact on the value of the stone. Heavily included stones may have a milky or hazy appearance. Quality rubies should be well cut to maximize the stone’s brilliance.
The Sanskrit word for ruby is ratnaraj, which means “the king of precious stones”. The word ruby comes from the Latin word rubeus, meaning red.