Ask Neil: Diamond clarity

Ask Neil: Diamond clarity

"I've been told that the 'clarity' of a diamond is the most crucial element to consider when buying - but I struggle to see the difference between most diamonds with distinct gradings. Is it really that important?"

- Vince, Weston-Super- Mare

"It’s important to recognise that retailers have pushed concepts such as clarity and a “4 C’s” approach over the last 4/5 years as part of their marketing strategy.

While clarity is important, it can be misunderstood, and sometimes used by sellers to push buyers in a certain direction during purchase.

Stones receive a clarity certification based on the number, size and visibility of their “inclusions” – microscopic pockets of minerals or other material, which affect the quality of light reflection within the stone.

Both the International Gemology Institute (IGI) and Gemological Institute of America (GIA), the two key organisations which govern gem standards, use the below system for grading a diamond’s clarity. Inclusions are difficult to spot with the naked eye, so my graphic here shows the differences you might spot while looking through a microscope:


It is important to note that most “small” stones below 0.45-0.5 carats in weight will not receive an official certification, since at this size clarity is less important, with imperfections being less visible and more likely to blend into the facets of the stone.

When buying in this smaller range, a hard and fast rule of a certain grade will be unhelpful - instead focus on how the level of clarity combines with other factors such as colour.

I have seen small stones with quite significant inclusions captivate the eye with a strong colour grading of E or F, and the right ring setting.

For stones of around 0.5 carats, I recommend securing a minimum clarity certification of around SI1 – for a single, solitaire-cut 0.5ct diamond, this will likely cost in the range of £2000-£2500, for example.

This grade will ensure there are minimal visible marks to the naked eye, and controls the price – then consider other aspects such as colour and cut. In my opinion this is a sweet spot for quality and price, and you can see below how inclusions start to get much more obvious when going from SI1 to SI2.

For larger diamonds, approaching the 0.75-1 carat range, the clarity will become more important to overall appearance.

You might consider increasing your benchmark to VS1-VS2, however prices will increase exponentially at this weight and above, and since these sizes are rarer, their valuation can be a lot less consistent.

You can compare the prices of stones of a particular certification online, and this will give you an idea of what is available, but the most satisfying way to find the right stone will always be an in-person conversation with a jewellery professional.

Give them some clear parameters for what you are looking for and they will do the rest – if the stone is for an engagement ring, it is particularly useful to find someone with metal crafting experience who will have an idea of how the stone can be set into a piece to maximise it’s potential."


Neil Rayment is a Goldsmith-accredited fine jewellery and metalcraft expert with over 30 years of experience in the industry.
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