Clarity refers to the internal features of a polished diamond. Generally the cleaner a diamond the rarer it is. Clarity is assessed at 10x magnification via the use of a loupe or microscope. For ease of perception, a stone is checked under an appropriate light source and preferably at the edge of the lightcone. Contrasting lighting conditions make it easier to identify less obvious inclusions. Both darkfield and brightfield illumination are preferred choices for clarity grading purposes.
Internal clarity grading standards follow a harmonized scale. The clarity grade always depends on the actual size, the number, the position and nature as well as the relief of any internal and external features present.
Flawless (FL) – applied only by the GIA – categorizes stones that are internally and externally impeccable. This grade may command a price premium of 2-3% over IF and is reserved for stones that are often stored in a vault or traded mostly as sealed goods. IF (Internally Flawless or Loupe clean in HRD) is the more commonly seen top grade. Such stones are totally devoid of internal features at 10x magnification. Minor surface graining (growth irregularities) and insignificant blemishes (external features such as a small nick or scratches) on the other hand are permissible. The wholesale trade however prices IF stones possessing minor surface graining closer to VVS1. This next lower grade VVS stands for a minute or ‘very very slight inclusions’ and distinguishes between VVS1 denoting inclusions that are ‘extremely’ difficult to see (for example 1 to 2 ‘pinpoints’) and VVS2 in which inclusions are just very difficult to notice. It is a very narrow clarity band and internal graining, for example, may push a stone from VVS1 all the way down to a VS1 grade in rare severe cases. VS refers to ‘very slightly’ included and stands for minor inclusions. In VS1 a feature (e.g. several pinpoints or a finely fractured so-called ‘bearded’ girdle) is usually difficult to spot whereas inVS2 (e.g. a ‘cloud’) it becomes somewhat easy to locate.
‘Slightly included’ SI1 and SI2 grades follow. SI1 diamonds have noticeable inclusions whereas SI2 stones contain obvious, easily seen inclusions. Typical features observed in SI grades include small gletzes and/or few crystal inclusions or black spots) under 10x magnification. SI grades are considered to be mostly eye clean. Particularly SI1 graded stones contain inclusions that are only rarely visible face-up. Larger SI2 diamonds, however, may contain slightly eye visible features. The grade SI3 has not been adopted by the leading labs, though it is useful in categorizing stones which closely resemble SI2 stones at first sight but are otherwise strictly regarded as ‘Included’ I1. Such diamonds make good ‘bluff’ stones. This can be relevant from a pricing standpoint. Included or Piqué goods (as they are known in Europe) conclude the clarity scale and contain features that no longer require magnification to be visible. Although I1 stones remain commercially relevant their beauty or durability maybe somewhat affected. They might possess a few feathers or several larger black graphite spots. The grades I2 and I3, on the other hand, are exclusively destined towards very inexpensive jewellery. I2 grade diamonds typically possess reduced brilliance and one or few heavy inclusions that may also affect durability. I3 stones are considered near-industrial grade. Their transparency tends to be low and durability is often seriously impeded.
‘Smalls’ and melée-sized diamonds are also graded according to above-mentioned grading standards, albeit often in a slightly more rudimentary and less exacting way.
Diamond clarity is complex and best assessed by professionals.
Pricing, especially across VS to SI grades, is ‘fluid’ and closely reflects the true nature and conspicuousness of the inclusions and not just the ‘certificate’ grade. In other words, the wholesale diamond market will apply different prices to two otherwise similar SI stones according to the relative beauty (quality) of SI1 inclusion (pattern). To illustrate this a minor white laterally situated fracture graded as SI1 may be visually more pleasing and less discernible than a centre black SI1! The first stone would understandably command a higher price than the latter. Furthermore, black VS and SI inclusions are also avoided in certain countries, particularly across Asia, where black spots are associated with unlucky superstitions.
At present, there is a global shift away from top qualities in the lower and intermediate price brackets as ever more knowledgeable consumers are discounting clarity in favour of size and colour given that VS and SI qualities are often more than enough. After all, there is little difference in actual perceived beauty between an IF and an SI1 and only in poor SI2 and I clarity grades do inclusions become actual flaws.
Clients should also be aware of manmade surface-reaching internal laser drill holes, which improve apparent clarity but not the actual clarity grade. Although the GIA grades laser drilled stones no different, the trade dislikes and severely discounts them. Consumers are best to avoid such diamonds.
Fancy coloured diamonds are graded the same way colourless ones are. However, the market puts less emphasis on clarity as part of its overall valuation. Though premiums are paid for IF and VVS grades due to an even more pronounced scarcity and overall demand tends to be slightly greater for VS2 or better grades, the importance of colour and cut truly overwhelms. The only exceptions are yellow or brown diamonds which due to relative abundance follow a valuation approach in clarity akin to that of D-Z colour diamonds. For most fancy coloured diamonds (such as pinks and reds) SI1 remains the benchmark, with SI2 being slightly discounted. Near-eye clean I1 clarity grades are acceptable in particularly rare and/or aesthetic fancy colours (for example large vivid greens) and do not necessarily hinder such diamonds from reaching incredible valuations.
Such exceptional diamonds are assessed more along the lines of traditional coloured gemstone grading, where colour is paramount and minor clarity issues are tolerated.