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The Gem Quarter, Gemstones














From candy to crimson, there's a whole vibrant spectrum just within these passionate hues.
From candy to crimson, there's a whole vibrant spectrum just within these passionate hues.

The Gem Quarter: Understanding colour - Candy to Crimson

Jeweller explores the vivid spectrum of red, pink and purple gemstones, from chemical quirks and crystal lattice deviations to exotic origins and mystical tales.

When it comes to gemstones, colour is king. Even beyond its artistic appeal for jewellery design, colour speaks to us on a psychological level – triggering memories, sparking passions and soothing spirits.

One of the most attractive and emotionally provocative colour palettes is that of red, pink and purple.

The entrancing vibrancy of these rich hues have captivated humans for centuries across diverse cultures from all corners of the Earth, speaking to passion, vitality, love, and majesty.

Any discussion of the red-spectrum gemstones must begin with that most iconic of gemstones – the ruby. In Sanskrit, it was known as ratnaraj – “the king of jewels”.

Prized by royalty not only in ancient India but throughout history and across the world, this deep orange-to-purplish red form of corundum was thought to increase vitality and wealth and bring success in love and battle.

Colourless in its purest state, corundum (aluminium oxide) is allochromatic, meaning it relies on trace impurities to create the appearance of colour.

To create the deep, vivid red of a ruby, chromium is present in the crystal lattice.

The amount of chromium present determines the strength of the colour, while the presence of other elements, such as iron, influence tone and hue.

The most chromium-rich rubies originate from Myanmar (Burma). Without iron present, they present as a vivid pinky-red and show fluorescence in sunlight, adding to their intensity. These gems form in white marble and are known as ‘pigeon’s blood’ rubies.

In contrast, Cambodian and Thai rubies form in iron- rich basalt, giving them a more orange-red colouring and low fluorescence. They are also notably darker than Burmese rubies.

African rubies – typically from Mozambique – also tend colour palettes is that of red, pink and purple. The to be darker, but a wide variety of hues are available.


Sapphire and spinel

Chromium is also responsible for the colour in pink sapphires, another variety of corundum. A mix of chromium and iron combine to form the sought-after orange-pink known as Padparadscha – meaning “lotus flower” in Sinhalese, the language spoken in Sri Lanka.

 Purple or violet sapphires contain a mixture of both titanium, which creates classic blue sapphires, and chromium, which adds the red-pink component.

"One of the most attractive and emotionally provocative colour palettes is that of red, pink and purple. The entrancing vibrancy of these rich hues have captivated humans for centuries across diverse cultures from all corners of the Earth, speaking to passion, vitality, love, and majesty."

Over the centuries – prior to modern scientific analysis – both rubies and pink sapphires were frequently confused for another gemstone: spinel.

Famously, the Black Prince’s Ruby – part of the British Crown Jewels – is, in fact, the largest uncut spinel in the world.

While spinels were first differentiated from rubies in 1783, they were not scientifically identified as such until the 1950s.Indeed, rubies and spinels are frequently found together.

The deep, vivid red of the Black Prince spinel is caused by chromium – the same element that produces ruby colour. Chromium is also responsible for the colour of pink spinels, which resemble fancy sapphires, while a combination of iron and chromium produces purple spinel.

The similarities between spinel and corundum are present in their formation; aluminium oxide may form corundum or combine with magnesia to form spinel.

Above: Arman Fine JewelleryAbove: Tiffany & Co
Above: BvlgariAbove: Van Cleef & ArpelsAbove: Van Cleef & Arpels

 

Above: Chow Tai FookAbove: Jewellery Theatre
Garnet and beryl

Another colour gemstone prized since ancient times is garnet. While this neosilicate forms in many different colours, it is best known for its deep red varieties; in Middle English, the word garnet simply means “dark red”.

Pyrope and almandine garnet range from purplish to brownish, with almandine – the most abundant member of the garnet family – tending to be darker than pyrope. Its colour comes from traces of iron in the crystal lattice.

"Another colour gemstone prized since ancient times is garnet. While this neosilicate forms in many different colours, it is best known for its deep red varieties; in Middle English, the word garnet simply means “dark red”.

Meanwhile, the crystal lattice of pyrope – meaning “fiery- eyed” in ancient Greek – is concentrated with magnesium and aluminium. It can range in colour from palest rose to scarlet, violet and indigo.

Violet-red garnets, known as rhodolite, are a mix of pyrope and almandine and are sometimes referred to as California ruby, Rocky Mountain ruby, and Bohemian garnet.

High iron and manganese concentrations can produce a particularly striking purple rhodolite, which is found in Mozambique.

Manganese is also responsible for the pretty pink hues of morganite, a variety of beryl (beryllium aluminium cyclosilicate). While the colour range for morganite is wide, moving from peach to salmon and purplish-pink, rosy tints are prized.

As a result, heat treatments may be applied to drive off yellow or orange undertones, leaving a purer pink shade.

Morganite with a naturally saturated colour is rare and valuable, and it is dichroic, meaning it shows two distinct colours – usually a pale pink and a darker, bluish pink – when viewed from different directions. This factor can make cutting for colour quite challenging.

A mixture of manganese and caesium oxide produces a deeper scarlet hue, known simply as red beryl. It is rarer and therefore less commercially available than other beryl varieties.

Tourmaline and topaz

Alongside beryl, one of the best-known gems for its colour variety is tourmaline; indeed, its name comes from the Sinhalese word toramalli, which means “gems of mixed colours”.

As in morganite, traces of manganese produce red and pink tourmaline – though pinks can also be created through irradiation.

Saturated red-to-pink tourmaline is known as rubellite, and these gems are frequently tinged with orange, purple or brown undertones.

"While tourmaline is prized in its own right – and favoured by many jewellers for its abundance and affordability – the most expensive rubellite imitates the saturation and intensity of ruby."

While tourmaline is prized in its own right – and favoured by many jewellers for its abundance and affordability – the most expensive rubellite imitates the saturation and intensity of ruby.

Nearly all tourmalines display pleochromism – meaning their hue, and sometimes tone, vary with the crystal’s orientation.

Pink tourmaline appears darker when viewed in the direction of the optic axis (that is, parallel to the length of the crystal), and lighter when viewed perpendicular to the optic axis.

Another gemstone displaying this optical phenomenon is topaz. Imperial topaz – specifically the pink-orange variety – is the most valuable of topaz colours.

Impurities and structural defects in the crystal lattice produce colour in topaz. The presence chromium results in a red or pink variety.

Brazilian reddish-brown topaz can be heat treated and slowly cooled to form pink and purple-red gems.

Brazil is also a rich source of amethyst, the purple variety of quartz. Ranging from pale lavender to vivid violet, amethyst colour is still something of a mystery to science.

It is speculated that trace iron atoms in the crystal lattice, combined with natural irradiation, is responsible.

Meanwhile, rose quartz – the delicate pink gem – is coloured by traces of titanium oxide or manganese.

While often sold as uncut crystals due to their cloudy and softly translucent appearance – the result of many tiny inclusions – high- quality rose quartz has clearer transparency, a deeper colour, and can be faceted.

Premium rose quartz is found in Madagascar, which is known for its colour saturation and asterism.

 


 

 

Burmese spinels are perhaps the most well known in the world for their colour and quality. Famous colours from the region include the ruby-like pigeon’s blood – a vivid red – and the pinkish red dubbed ‘Jedi spinel’.

Burma (Myanmar) is also known for producing perfect octahedral spinel crystals that are so well formed and polished, the locals call it Nat Thwe which translates into ‘cut by the spirits’ or ‘angel cut’.

Mining in the Mogok region has been recorded as far back as the 6th Century CE. Mogok was kept under strict control by its different rulers until modern times.

From 1889 to 1931, when Burma was a British colony, mining in Mogok was conducted by British firm Burma Ruby Mines. Its studies showed that the highest- yielding deposits would be underneath a settlement, which lead to the relocation of the entire Mogok village.

In 1929, prolonged monsoon rainstorms flooded the mine, which formed the lake in the middle of Mogok as we see it today.

Another important – though not well-known – source of fluorescent hot pink spinel is in a remote mountainous area call Namya, Nanya, or Nanyazeik, in Kachin state, upper Burma.

Mining activities only began in the late ’90s and production is kept minimal due to the difficult terrain.

Source: Mays Gems & Jewellery

 

 

 

 

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