…and all you need to know about them
If diamonds are a girl’s best friend, then the rest of the gemstones make extraordinary acquaintances. Our relationship with precious gems seems timeless; humans have always loved to decorate themselves. We have long been drawn in by the sparkle and allure of gemstones and have prized them highly. Most of us also feel an affinity towards a particular stone, whether it be our birthstone, or a favourite for personal or aesthetic reasons. But what is it that makes gemstones just so special? And what gives particular value to specific stones? In hope to find the answers let’s have a closer examination of the most important gemstones.
We already know that gemstones can be exquisitely beautiful, from vintage diamond studs to antique sapphire rings, but that is not the only thing which gives them value. Rareness and hardness are also contributing factors to finding your perfect stone. It is difficult to create an objective scale of value for gemstones; their value can be personal and objective. It really all depends on what you are looking for. There are however, some factors that we can use to figure out the value of certain stones…
Carat weight is perhaps the main consideration. The price of a gemstone rises quickly in relation to an increase in carat weight. For example, if a 0.5 carat diamond were to fetch £250 that would make the cost £500 per carat. Whereas if a similar quality diamond weighed 2 carats it could fetch a much higher price, say £4,000, making the price per carat £2,000. This disproportionate increase in price per carat is one of the reasons why large diamond solitaire rings are of such high value.
Colour is also of great importance. A very slight difference in colour can equate to a high rise in the value of a stone. Because of this, jewelers sometimes choose to design a piece with a few, smaller, gemstones of a high quality colour rather than feature a single large stone. This makes sure the colour is fabulous while minimizing the cost.
Another factor at play is, of course, availability. If a gemstone is particularly rare you are likely to see the value rocket as a result, and vice versa. We have seen this in action throughout history. When important diamond mines were discovered (for example in South Africa in the 1870s) production of diamond jewellery increased. This sudden availability also had an effect on the cuts used. After discovering the South African mines for instance, brilliant cuts were used more often, as cutting losses and waste wasn’t as big of a concern. The opposite can also occur: during the Boer war (1899-1902) for example, it became much more difficult to source diamonds and they therefore became rarer within jewellery.
Finally, the hardness of a stone must be considered. Gemstone hardness is measured by the Mohs’ scale which classifies materials in order of how easily they can scratch softer stones and how easily they themselves can be scratched. Working our way through this scale (hardest first) let’s explore some of the properties of the most important gemstones…
There is a reason that ‘diamonds are forever’. They hold pride of place right at the top of the Mohs’ scale meaning that they are incredibly hard and tend to outlast their setting. They are actually a crystalline form of carbon and often occur naturally as octahedron. Originally they were left in this form, but advancements in cutting techniques have seen their shape evolve over time.
Despite their impressive hardness they are not actually unbreakable. It is still possible to chip or even shatter a diamond, especially one which already has a fault. As well as their hardness, diamonds are also valued for their superior light dispersion (the ability to spate bands of colour and split white light). This is what gives us the sparkle that we are oh so obsessed with!
After diamonds, one step down on the Mohs’ scale we find corundum. Corundum is made of aluminum oxide and is the material that gives us rubies and sapphires. Pre-1800, rubies and sapphires were not in fact recognized as corundums and were instead confused with softer stones such as garnets and spinel.
The perfect ruby would be a bright rich red with a tiny hint of blue. If rubies are ever light enough to be considered pink they must instead be called ‘pink sapphires’.
The ideal sapphire would be a strong cornflower blue.
Variations of clear corundum also exist, they are known as white sapphires. They could perhaps be mistaken for diamonds, but do not have the same dispersion levels.
It is extremely rare to find a ‘perfect’ emerald. Often, inclusions (known as jardin or ‘garden’ in relation to emeralds) are celebrated on these stones as they prove authenticity. A negative element to these faults however, is the fact that they make emeralds more fragile despite their inherent hardness.
Aquamarines and emeralds are commonly boiled in oil to improve their clarity. They are both most often cut in the rectangular step cut shape.
There are many varieties and colours of this gemstone ranging from yellow to brown. The most valuable members of the Chrysobel family are alexandrite and ‘cat’s eye chrysobel’. The former of the two is named after Tsar Alexander II and can range in colour from purple/red to green/blue.
Cat’s eye chrysobel on the other hand, is normally found in colours that could be described as ‘milk and honey’. These variations are always cabochon cut.
This gemstone comes in shades of blue pink and yellow. The most valuable colours of topaz however are pink and ‘golden sherry coloured’.
Although it is much less hard, spinel has historically been confused with ruby. They are often found together and share a red hue. Spinel however, can also come in yellow, blue, pink and orange varieties. It wasn’t until around 1830 that these similar looking stones were recognized as different.
Garnet was a favoured gemstone in jewellery manufacture centuries ago. It was also popular during the Victorian era. It is normally an orangey brown colour, but can come in six different varieties ranging from green to yellow, to orange to red.
They are often either cabochon or rose cut. They also have a history of being set with coloured foil behind them in order to enhance their colour.
The most common colours of tourmaline are green and pink; however the highest value lies in the red and emerald green varieties. This gemstone is often cut in such a way that two or more colours are revealed within one stone.
What we know today as zircon was once known as ‘Jacinth’. It is normally white in colour but blue variations are also common. Furthermore, there is also a variety known as Hyacinth which is red or brown in colour. Zircon can be quite brittle, but their true value comes from their sparkle; they have a very high refractive index and shine almost as brightly as diamonds. They are normally heated to enhance their bright blue colour.
7th on the Mohs’ scale and the last ‘hard’ gemstone we will look at today is quartz. Anything further down the scale than quartz starts to get much more vulnerable and soft- a potential problem when setting it into a ring.
There are many varieties of quartz including: Smokey quartz (brown), pink quartz, rock crystal (clear), aventurine (green), tiger’s eye (yellow), hawk’s eye (blue), chalcedony (cam be orange to brown to red), chrysoprase (dark green), agate (banded or layered with different colours), onyx (a black and white variety of agate), Jasper (can be a variety of colours), and finally, Opal.
Opal, perhaps the most well-known variety of quartz can come in a variety of colours and forms. Fire opals showcase a fiery red/orange colour, whereas white opals are a light milky colour. Water opals are clear or colourless, and the rare black opal (despite its name) is usually a very dark grey, blue or green.
All of these stunning gemstones have their own pros and cons. Although objective value can be roughly determined by weight, colour and availability, it really comes down to personal preference. Items of jewellery featuring any of the above stones (of a high quality) are sure to be show-stopping! So whether you choose your favourite gemstone based on colour, light refraction, hardness, or uniqueness, I’m sure you’ll find the most important gemstone for you.
Delilah Kealy-Roberts – Sales and Digital Assistant
Delilah joined the AC Silver team as a Sales & Digital Assistant in 2017 after completing her degree in English Literature at Leeds University. Delilah possesses a passion for jewellery and antiquities combined with an interest in blogging and social media.