Sapphire: gem of the sky

Sapphires are found in various hues, but while blue is the most common of its colours, it is not the only one the gemstone boasts – everything from golden sunrise to deep indigo and the subtle violet of twilight is possible, as are colourless, grey, pink, orange, green and brown varieties. 

 

Such deviations from the norm are called fancy sapphires; however, a vivid, cornflower blue, verging on violet is considered the gem's most valuable shade. Indeed, a sapphire too dark or light in colour has a much lower value than one with more vivid hues. The lustre of a sapphire means it shines more than glass (vitreous) but less than diamond (adamantine).  

 

Sapphire is a form of the mineral corundum – a colourless mineral formed from crystallised aluminium oxide. In fact, all corundum in all colours belongs to the sapphire family except for red, which is ruby. 

 

The colour of the sapphire is formed from different types of trace elements within the crystal – a hexagonal bi-pyramid. While there are several possible causes for the sapphire's blue colouration, it is most likely tinted by the presence of iron and titanium in the corundum structure.  

 

There are various possible explanations for the origins of the word “sapphire” but it could have derived from several ancient languages – the Arabic, safir and the Latin, sapphirus are two possibilities; however, the most plausible explanation is the Greek word sappheiros that denoted the Arabian Sea island of Sappherine, the source of the gem in ancient times. 

 

Folklore suggests the sapphire was believed to signify purity of the soul. During the Middle Ages, priests wore sapphires around their necks as protection from tainted thoughts and medieval kings wore sapphires to protect them from harm and envy. 

 

The French believed that the sapphire transformed stupidity to wisdom, and petulance to good temper. Warriors presented their wives with sapphire necklaces so they would remain faithful; the stone's colour was believed to darken if worn by an adulterer. 

 

Today, sapphires are mainly sourced from Thailand, Sri Lanka, Australia – the source of yellow and green varieties – Madagascar and Tanzania. Most of the fine blue sapphires on today's market are from Sri Lanka and Madagascar. Kashmir, Burma, Kanchanaburi in Thailand and Pailin in Cambodia are also renowned for deep blue sapphires of limited supply. 

 

Cut, colour intensity, consistency and purity are the deciding factors in a sapphire's value. The finest sapphire should not contain any secondary colours or nuances because this will diminish its value and beauty.  

Despite being a hard gem, rating nine on Moh's scale, sapphire must still be treated with care. The gem is slightly brittle and can develop internal flaws and cracks if dropped on a hard surface or delivered a sharp blow. 

 

There is no true cleavage point in corundum, though a false cleavage – a parting – may be present in some examples. 

 

Sapphire is the birthstone of September and the gemstone for the 5th and 45th wedding anniversaries. For its striking beauty and versatility, sapphire-set jewellery remains ever-popular.