Friends and clients often ask me: "What is the main quality to look for in a stone, is it the colour, the clarity or the cut?" To be honest, it is the combination of all three that creates each stone's beauty and there is no exact formula to follow. The beauty, after all, is in the eye of the beholder.
Although diamonds are graded on their 4Cs (colour, cut, clarity, carat weight), when selecting coloured gemstones, the rules apply quite differently. Even very tiny inclusions can significantly lower the value of a diamond, but it is the colour of gemstones that play the main role.
You might have heard terms such as VVS, VS and SI used when talking about diamonds, but these categories do not apply to gemstones. Although GIA's International Diamond Grading System is widely recognised, there is no international standard for grading clarity in coloured gems.
With so much information at our fingertips, gemstone research can become confusing. As a GIA certified gemologist, I would like to share some information I learned during my studies as well as over my 10 years spent working in the gemstone, diamond and jewellery industry.
Today’s post is primarily dedicated to gemstone clarity, let’s begin!
What is clarity?
Clarity is a gemstone’s relative freedom from clarity characteristics.
Clarity grading is actually divided into two parts. Things inside the stone, referred to as inclusions and things outside the stone referred to as blemishes on the surface of the stone.
Inclusions - Characteristics enclosed within as stone
Crystals - mineral crystals trapped within a gem, can be rounded or angular.
Fingerprint inclusions - a pattern formed by trapped droplets of fluid, resemble a human fingerprint.
Feather - a fracture inside the stone.
Cavity - an opening that extends into a gem from the surface.
Cloud - a hazy or milky area.
Chip - a damaged part on a gem.
Needles - long, thin solid crystals. A group of fine needles is called “silk”.
Take a look at these needles in a green sapphire below!
Silk inclusions are also responsible for the existence of gemstone that display star and cat’s eye effects, such as star sapphires and cat’s eye chrysoberyl.
Three phase inclusions - these contain a solid square or rectangular crystal and a round gas bubble, surrounded by liquid. Take a look below, isn’t that fascinating?
Inclusions can have a negative meaning for some, however they are essential in helping us identify gemstones, indicate their formation process and sometimes even hint at their origin.
For example, for many years, emeralds that contained “three phase inclusions” were considered Colombian. New studies, however, have shown that emeralds from Afghanistan and Zambia can also have these inclusions.
The size and nature of the inclusions is important, a single large feather (left) can be much more of a threat to a stone than a large cloud or fingerprint (right). A cavity or fracture that reaches the surface of the stone is more risky and can cause durability issues, compared to a small feather completely enclosed within a stone, which is not as hazardous.
Stay tuned for a blog post on gemstone durability coming soon!
An inclusion’s position is also important. Those situated right under the table (front and centre) are more visible than those in the pavilion (lower part of the stone).
If the stone has no inclusions visible to the unaided eye, it is referred to as “eye clean”.
Gemstones with no inclusions whatsoever often causes suspicion, it may be a sign of a synthetic stone (created in a lab) or even a glass or plastic imitation.
Some inclusions are even desirable by customers and collectors. Take a look at these horsetail inclusions, they are one-of-a-kind and help us identify the stone as a demantoid garnet.
Blemishes - Characteristics on the surface of the stone
Scratch - a scrape on the surface, often looks like a thin white line.
Abrasions - small nicks seen on the facets edges, typically caused by regular wear.
Depending on the stone’s hardness, some gemstones are more likely to get abraded over time than others.
When looking at stones, it is important to clean the surface first, as dust or grease can look like blemishes.
For more information, visit my previous blog:
Inclusions can offer proof of presence or absence of treatments.
For example, a damaged crystal inside a sapphire or broken silk can be a sign of heat treatment in a sapphire. As almost 99% of sapphires are heat treated to enhance and stabilise the colour, these inclusions are fairly common. Check out this crystal with a halo around it, a classic sign of heat treatment.
As emeralds are typically fractured inside, a common treatment known as oiling is used and is an industry standard. The process involves filling of surface-reaching breaks with various oils and resins. With roughly 90% of all emeralds undergoing this treatment, finding an untreated emerald is virtually impossible and will be reflected in the significantly higher price. Take a look at this before and after example.
So how is gemstone clarity graded?
Some gemstones are more likely to be included than others. For example the majority of emeralds are fairly included, showing significant fractures within the stone that can be seen without magnification. Therefore finding an emerald without inclusions is almost impossible.
Emerald is a part of the Beryl family. Interestingly, Morganite and Aquamarine that are also a part of the same family show virtually no inclusions, even under magnification.
Let’s take a closer look at how gemstones fall into each clarity category.
Eye clean, meaning you will not see inclusions with your naked eye, without magnification.
Aquamarine, Morganite, Green Tourmaline, Blue Zircon, Tanzanite
Some visible inclusions.
Alexandrite, Peridot, Spinel, Pink tourmaline, Sapphires of all colours,
Quartz (e.g. Amethyst, Citrine), all Garnets (including Rhodolite, Tsavorite etc)
Almost always severely included.
Emerald, Watermelon Tourmaline
To find out more about your birthstone, check out this blog: Beauty and Power
With such a wide variety of gemstones available, clarity is relative when grading coloured stones. It would not be fair to grade a Type I stone such as morganite which shows virtually no inclusions on the same scale as a Type III stone like emerald which is almost always included.
There are however further quality divisions for each stone. Emeralds for example are available in a range of qualities from high to low at different price points.
A final note
It is important to remember that when it comes to coloured gemstones, it is their colour rather than clarity that is of absolute importance. This however is not the case when dealing with diamonds, where clarity and the lack of inclusions is a huge factor affecting its grading and has a big effect on the value.
As part of the Tsarina Gems experience, I love to share my knowledge and guidance to help you select the stone of your dreams that is also a durable option.
When working together to select your gemstones, I carefully inspect each stone for durability issues before presenting it to you. But ultimately it is the colour of the gemstones and its overall look that should speak to you.
I love sharing what goes into the gemstone selection process and the journey each stone takes to become a wonderful new piece of jewellery. Visit my recent gemstone projects involving an exquisite purple sapphire, a dreamy opal and a stunning green sapphire.
These three beauties are available for purchase, please contact us for more details.
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