The Major Gemstones | The Cardinal Gemstones
When it comes to gemstones, there are various considerations such as rarity and individual attributes that have lead to certain gemstones being regarded as more valuable than others. Traditionally five were considered the rarest and most precious of all, and these were known as the Cardinal Gemstones. The term Cardinal Gemstone refers to the use of these gemstones by royalty and for religiously significant purposes. They were diamond, emerald, sapphire, ruby, and amethyst. Over time, vast deposits of amethyst were found, effectively lowering the value of stone, causing it to be reclassified as 'semi-precious'. This lead to amethyst being bumped off the Cardinal Gemstones list, leaving diamond, emerald, sapphire and ruby to be known as the Major Gemstones.
Here's a little overview of each.
The diamond is certainly enjoying regard as the most popular of the major gemstones, thanks to a 1930s de Beers marketing campaign that stated "Diamonds are Forever".
Diamond is the hardest naturally occurring substance on Earth. Formed millions of years ago deep below the Earth's crust, diamonds have been thrust to the surface in earthquakes and volcanic eruptions. Up until the mid-nineteenth century, almost all diamonds were found in India, but in 1867 a huge diamond was found in an African riverbed, and following extensive exploration and mining, now almost every diamond sold today originates in Africa. It is a myth that diamonds are rare. Yes, they used to be until the African supplies were discovered. but de Beers controls 90% of the world's diamond mines and keeps vast quantities held in reserve to control the retail price with supply and demand. Diamonds occur in many different colours. "White" (clear) is the colour we are most familiar with, but they also occur in grey, black, blue, yellow, pink, green, red and brown depending on the chemical inclusions at its time of creation. Coloured diamonds, depending on the desirability of the colour, can command much higher prices than clear diamonds.
Diamonds are pure carbon
The only thing that can cut a diamond, is another diamond
Diamond is the birthstone for April
Diamond is the anniversary stone for the 60th year
'Black diamonds" are found only in South America and are thought to have arrived in meteorites.
Emeralds are a form of the mineral beryl, a family that also includes aquamarine and morganite.
Most emeralds come from deposits in Africa and South America, where they can grow quite big - up to 180,000 carats!
Emeralds are usually a vivid green, but also occur in blue-green, and almost all have inclusions called 'jardin', tiny lines that can make the gemstone brittle. It was because of these inclusions that the emerald cut was developed, the elongated rectangle works well with the inclusions to preserve the integrity of the stone. Most emerald gemstones will have been treated with an oil to hide the inclusions and so require careful cleaning.
Emeralds are the birthstone for May
Emeralds are the anniversary stone for the 55th year
Top quality emeralds can be worth more than top quality diamonds
Emeralds have been mined and used by humans for over 4000 years.
Emerald has a hardness between 7.5 and 8 on the Mohs scale.
A sapphire is a gemstone quality variant of the mineral corundum. While sapphires are typically thought of as blue, the corundum mineral comes in other colours too, known as the fancy sapphires. Fancy sapphires can be yellow sapphire, pink sapphire, green sapphire etc., but never red. Red sapphires are known as rubies!
Sapphires often have needle-like inclusions called rutile, decreasing the transparency of the gem. The most valuable sapphires are the ones with the least inclusions, except for when those inclusions form a star-like pattern called asterism. Asterism will most often present as a six-pointed star, though some sapphires have been found with 12-pointed stars. Sapphires with asterism are usually polished en cabochon to display the star, whereas transparent sapphires are cut to show their sparkle.
In the middle ages the Pope began the tradition of giving sapphire ecclesiastical rings to bishops and cardinals as they were thought to be a link to Heaven and promoted the purity of thought.
Sapphire is the birthstone for September
Sapphires have long been a favourite amongst royalty, hence the colour being referred to as "Royal Blue"
Sapphire is the anniversary stone of the 45th year.
Corundum, the mineral of which Sapphire and Ruby are formed, are a 9 on the Mohs hardness scale - second only to diamond.
Genuine rubies are amongst the most expensive and valuable gemstones you can buy. Rubies are a red form of the mineral corundum, with all other colours and forms of corundum being called Sapphire. In some instances where the colour is not deep or red enough, these red corundums will be marketed as Pink Sapphires rather than as rubies.
Like sapphire, rubies have inclusions called rutiles, with some inclusions forming a star radiating from the centre of the gem. Rubies displaying this kind of inclusion are called 'Star Rubies'
Large transparent rubies of a deep red colour can fetch many thousands of dollars per carat, and far more than diamonds!
The most valuable ruby gemstones are a transparent deep red to purple-red (a colour referred to as pigeon's blood), and those found in SE Asia are considered the most desirable.
Ruby is the birthstone for July
Ruby is the anniversary stone for 40 years
Ruby has a score of 9 on the Mohs hardness scale.
Amethyst is one of the original Cardinal Gemstones, but not one of the modern Major Gemstones. In the Old World, amethyst was considered rare and precious, but huge deposits were found in Brazil in the 19th century, effectively knocking them out of the rarity league and leading to the formation of a separate group of Major Gemstones that excluded amethyst.
Amethysts are a form of quartz found in geodes (large hollow rocks). Some amethyst geodes are so big a person can easily stand up in them!
Amethyst is the same form of quartz as citrine, and amethyst can be converted to citrine in the laboratory when exposed to a heat treatment.
Amethyst is the birthstone for February
Amethyst isn't traditionally an anniversary stone, but modern charts place it variously at 6 years, 17 years and 33 years depending on which you look at
Amethyst has a hardness of 7 on the Mohs scale
The future of the Major Gemstones
Since the Cardinal and Major Gemstone lists were created, there have been numerous gemstones discovered far rarer than the above. In fact, none of the above would even feature in the top ten of the rarest gemstones known today, so - who knows - maybe the list of Major Gemstones will get an update. Now wouldn't that set the jewellery world into a spin!