If, like many people, you are shopping for AAA grade sapphires or tanzanites in South Africa right now, you must read this article. These blue gemstones are popular in South Africa, particularly when it comes to engagement rings (although you should never consider tanzanite for an engagement ring, ever!) but there is a huge amount of confusion when it comes to certification of these gemstones.

Compared to coloured gemstones, diamonds are simple. The GIA-established 4C’s grading system is a universal standard, recognised world wide and, for the most part, you can be sure that you’re getting what the diamond certificate says.

Coloured gemstones such as sapphire, ruby, tanzanite and emerald are a whole different ball game. There is, as it currently stands, no universally accepted certification scheme for any coloured gemstones. What that means is that unlike the diamond industry, there is no set of standard colour, clarity or cut examples against which a particular gemstone can be measured or compared. There is nobody to say what actually defines a AAA tanzanite or a AAA sapphire; nobody to define the minimum criteria.

Coloured gemstones are far more complex than diamonds when it comes to grading and identifying their quality. Colour can be broken down into three distinct parts: hue, saturation and tone.

Gemstone colour

At its most basic level, the hue is the colour that a gemstone visually displays to the naked eye (think green, or blue, or yellow, or orange, for instance). Most gemstones, however, display a hue that has more than one colour in it – think of a painter mixing colours on her palette to make an orangey-yellow, or a greeny-blue. The GIA has a colour wheel of 27 different hues possible in coloured gemstones.


The GIA colour wheel, showing a complete range of colours, as identified by their laboratories. Source: GIA

Tone refers to a gemstone’s relative lightness or darkness. Ideally, a coloured gemstone like sapphire, ruby or tanzanite shouldn’t be too light, or too dark. It should be visually appealing and, dare one say it “just right” (although, what’s visually appealing and “just right is exceptionally subjective and will vary from one person to the next).

Finally, saturation refers to the amount of colour in a gemstone. Think of a glass of Oros orange juice (or Kool-Aid for our international readers) that you might mix up for your children. If you take two, equal 250ml glasses of water and add a teaspoon (5ml) of Oros to  one and add a 10 teaspoons (50ml) to the other, the one with 50ml Oros will be far more saturated than the one with only 5ml in it. Gemstones with low levels of saturation are sometimes called “pastel” whilst those with high levels of Saturday are called “vivid”.

Now, think about how many combinations of grades of colour you can get in a gemstone when you take into account the hue, tone and saturation. When you realise that it’s virtually impossible to have a universal sample set of all possible colour combinations, you can start to understand the challenges of grading and certifying sapphires, rubies, emeralds and tanzanites.

Emerald rings South Africa

An example of an exceptional quality emerald (left) vs a lower quality emerald (right). Look at the differences in vividness of colour, overall hue and saturation and inclusions. It’s not hard to see that the emerald on the left is far superior in quality to the one on the right.


AAA+ tanzanite certificate

An example of an EGL (European Gemological Laboratory) certified tanzanite, graded as a “Vivid +” (AAA+) quality colour.

Let’s look at these factors and variables in the context of a “grading” system you might have seen online, ranging from “A” to “AA”, “AAA” and even “AAA+” or “AAAA”. The first question we have to ask is what the benchmark is for a “AA” or “AAA” gemstone, be it sapphire, tanzanite or ruby.

The answer is that there is no benchmark!

Vivid colour grade tanzanite card

An independent tanzanite identification card indicating a Vivid colour grade for this tanzanite.

There is no set of sapphire (for example) standards that a person grading a sapphire can compare to see if the sapphire is a AA or AAA or AAAA. That’s the first challenge. The second challenge is that it’s not just the colour of the gemstone that determines its quality and value. You must take clarity and cut into consideration too.

Gemstone clarity

The clarity of the gemstone is equally important when comparing one gemstone to another. Most coloured gemstones have inclusions in them and these may range from being what we call eye clean (no imperfections visible to the naked eye), to a few imperfections to being heavily included. Generally, moderately to heavily included gemstones will have inclusions that you can see with the naked eye.

Included morganite vs eye clean morganite

A comparison of a morganite purchased online from a Thai website, by one of our clients. The morganite was described as “Lightly Included” but the inclusions are very visible to the naked eye (left image). Compare this to the image on the right, which is one of the morganites we supplied to one of our valued clients.

Again, you must understand that there is no benchmark as to what classifies as a “lightly included” gemstone compared to a “heavily included” gemstone. So, is the gemstone you’re purchasing online that is accompanied by a “certificate” stating that the gem is “lightly included’, truly lightly included or does it have more inclusions than an industry expert would expect?

Gemstone cut

You’ve also got to consider the cut of the coloured gemstone you’re purchasing. When grading the cut of a round brilliant diamond, the GIA will grade the cut on a scale from “Excellent” to “Poor”, depending on how close the mathematical proportions of the diamond are to the ideal standard. Diamonds are cut to give maximum sparkle, fire and brilliance, and measurements are based on the refractive and reflective physical properties of the diamond.

Coloured gemstones are cut to maximise colour and visual appeal, so you cannot expect to find the ideal proportions that you would find in a diamond. Some coloured gemstones are cut very deep (leading to a heavier carat weight) and others are cut quite shallow (leading to a lighter carat weight). This means that two round tanzanites, both 7mm in diameter, might have two radically different carat weights.

Certified sapphires in South Africa

An EGL certificate for a natural sapphire, indicating a greyish, violet-blue colour, lightly included clarity and very good finish.

What’s more important when looking at coloured gemstones is the overall look of the shape and faceting of the gemstone. Is it symmetrical, or is one side longer, or more curved, or more angular than another side? How well do the facets line up with each other? Is the culet in the centre of the gem, or off-centre? Does the gemstone have a window in it? (A window is an area where the colour appears to be see-through or insipid and occurs when crown or pavilion angles are cut shallowly).

What is AAA tanzanite or AAAA sapphire in South Africa?

The answer is that there is no clear definition of this, so it’s a case of buyer beware when you’re shopping online for gemstones (particularly from overseas locations such as India or Thailand). You’re essentially buying blind, with no real idea of what you’re going to receive, irrespective of what the accompanying “certificate” might say. You might think you’re purchasing an out-of-this-world deal but check your enthusiasm first, because it’s unlikely there will be a refund policy on these gems.

Sapphire identification card South Africa

An AGL (African Gemological Laboratory) sapphire identification card for a bluish green (teal or peacock) sapphire.

There’s one other thing to bear in mind when you’re shopping for coloured gemstone jewellery in South Africa. Many websites are using CAD renderings of ring designs to show you what a ring design will look like. Please understand that the CAD renderings don’t show actual gemstones, so the colour of the gemstone you get might be radically different from what the CAD you’ve added to your shopping cart is. A website that allows you to swop between setting an AA, AAA or AAA gemstone (where the tone and saturation of the CAD gemstone is digitally altered) is not going to supply you with a gemstone the exact colour of the ring you’ve just added to the cart – because it’s a computer rendering, not an actual gemstone.

CAD design sapphire ring South Africa

A CAD rendering of a ring design we did for a client prior to manufacturing a peacock sapphire ring for her. Note how the colour of the sapphire and the colour of the rose gold on the design is completely artificial.

Our hope is that this article helps you understand the amount of misinformation on e-commerce jewellery websites regarding the quality and certification of coloured stones. Our suggestion would always be to look at gemstones in person, if possible, prior to purchase, or to make a purchase from a trusted supplier who has a great track record and reputation.

If you’re uncertain about anything regarding coloured gemstones, feel free to reach out to Katannuta Diamonds, where our owner Clare Appleyard will be happy to answer all your questions.