Some content on this page are contributed by Good Old Gold, with thanks.
Know the Clarity
You would want to know the clarity of the diamond because it affects the price in a big way. It would be a folly to ignore the diamonds clarity as it is a sure way to get ripped off.
Get it Certified or Verified
I do not trust the jewellers in Singapore to do a decent certification on clarity. I would insist on a report by a reputable lab. Alternatively, make sure the store has a return policy and bring the diamond to an independent appraiser. The cost of appraisal is usually small compared to the price of the diamond.
Has the Diamond Been Clarity Enhanced?
Lots of diamonds nowadays are clarity enhanced. There is nothing wrong with buying clarity enhanced diamonds. However, it is important to pay the right price for what you buy. Find out the clarity grade before the enhancement process to determine the price you should be paying. When in doubt, do not buy clarity enhanced diamonds at all.
I hear nonsense from people regarding clarity grades all the time, especially from Singaporean women who obtain all sorts of misinformation from their friends and colleages. They say things like, "Do not buy a VS diamond. A VVS2 is bad enough."
I think part of their ignorance is fuelled by the bad grading standards of diamonds sold in shopping centres and neighbourhood stores. The diamonds graded inhouse are poorly graded. They probably grade SI diamonds as VS and VS diamonds as VVS, so that they can sell them for more. Unfortunately, Singaproeans do not know any better.
In reality, it takes a rare individual with microscopic vision to see inclusions in VS diamonds. You certainly cannot do it with 20/20 vision.
Buy the Clarity Grade You Need
Safety in choice combined with reason in cost lies at the mid-point of clarity grading - the VS2 diamond. Better quality lies above it, less quality lies below it.
The risk of eye visible inclusions rises rapidly below VS2, while the getting a higher clarity grade lowers the chance of a visible inclusion. Bear in mind that getting a higher clarity grade does not really improve the beauty of a diamond. (If you cannot see the inclusion, it is as good as not being there.) It just lowers the probability of that the inclusions are eye visible. For instance, it is almost impossible to spot an inclusion in a VVS diamond with the naked eye.
As it is still unlikely (but not impossible) that a person can see the inclusion of a VS2 diamond face-up, this clarity grade offers very good value.
Some people argue that if you can find SI diamonds that are 'eye clean', they offer the best value. But for an engagement ring that is worn ever so often, the inclusions may become visible if your fiance stares at it long enough. Being 'eye clean' means that the inclusions are not visible by casual observers who do not stare at the diamond over a long periods.
Hence, know what you are buying into, and buy the clarity grade you are comfortable with.
Do Not Buy Diamonds Graded as I - Included
They are ugly things, good only for cutting glass.
Relationship Between Cut and Clarity
A well cut diamond reflects so much light that inclusions are hidden by the blinding light. So, it is far more important for lower clarity diamonds to be cut well.
Always Check the Diamond Visually
Remember that the clarity grade of the diamond is determined by the grader by looking at it face up, and directly at the pavilion. Graders do not grade the side view of the diamond.
There may be an inclusion that is very obvious and disturbing when viewed from the side.
If you have a setting that is very open, like tension settings or a 4 prong setting, the sides of the diamond will be very visible. If you plan to have such a setting, make sure that the diamond is eye-clean from the side as well. Click on the image on the right to see what a small inclusion on the VS2 diamond can actually look like.
Also, the diamond may appear cloudy because of thin wispy inclusions all over the diamond that does not affect the clarity grade. This would not a very attractive diamond.
Therefore, it is important to check the diamond visually, or get someone trustworthy to do it for you, right before the purchase. It is important to look at the diamond from the side, and check for general cloudiness, or any other flaws visible. Afterall, there can never be a fixed rule or grade on general beauty.
By the way, girdle reflections (as in the picture on the left) are not inclusions. They are quite normal and it can be seen in all diamonds.