A guide for buying a polished diamond

Diamond Grading

At least once in life, when the time comes to buy a diamond engagement ring, when you start entering a few jewelry stores or go on to diamond websites, only then you realize that it is not easy at all.

There is a huge selection of diamonds size, many shapes, many colors with strange grade names you have probably never heard before, clarities of the diamond which you probably don’t understand if it is important or not, and of course, at the end, each diamond has a different price.

You might happen to see the same shape, size, color and clarity diamond in two different stores, but the prices are not the same… This alone can confuse you when you are planning to make an investment which will stay with you for many years.

Yes, I agree, buying a diamond is not very easy, even veteran diamond wholesalers sometimes have difficulties deciding between two similar stones.

For these reasons, I decided to write this diamond-buying guide, which you can review prior to buying a diamond. Hopefully, it will help you choose the most suitable diamond and save you some money on your shopping spree.

diamond books

Because most diamonds look almost the same to people who are not from the diamond industry, the diamond grading system is intended to help understand the diamonds’ price differences.

What is diamonds grading?

In the 1940s, the GIA (Gemological Institute of America) established the “4 C’s” and the International Diamond Grading System- a worldwide standard for evaluating a diamond’s quality.

The diamonds industry adapted the 4 C’s as the primary grading of polished diamonds, and those 4 C’s are the universal language for anyone who wants to describe the quality of a diamond.

The 4 C’s are Carat (weight), Color, Cut and clarity.

In the large diamond industry, who has the authority to decide what the value of each of the 4 C’s parameters is?

The answer is – the Gemological Institutes are the authority, or should I say the gemological laboratories for grading polished diamonds.

Gemological Institutes

The gemological laboratories are those who judge each diamond, they do the job objectively and they do it for you.

The most common known diamond grading laboratories are:

  • GIA - Gemological Institute of America.
  • IGI - International Gemological Institute.
  • HRD - Hoge Raad Voor Diamant.
  • EGL - European Gemological Laboratory.
  • AGS - American Gem Society.
  • IGL - International Gemological Laboratories.

Diamond wholesalers and retailers from different parts of the world adopted a different diamond-grading laboratory. For example, in the USA, the GIA is the most popular diamond-grading laboratory, in Europe, jewelry stores prefer the HRD and IGI, and in the Far East, jewelry stores sell using their own certificates or those of IGI and GIA.

A new problem arose when professional traders noticed a different grading for the same polished diamond among the different laboratories.

Which is the most professional institute we can rely on?

I would say, with my 40 years’ experience that the GIA is the most accurate and reliable institute, and I have always recommend my customers from all over the world to purchase polished diamonds only with the attached GIA Certificate.

Please look at a short video clip made by the GIA

We can now move on to learn the meaning of the 4 C’s.

What are the 4 Cs of a loose polished diamond?


A diamond's carat refers to the weight of the stone.

1 carat is equivalent to 0.2 grams

The weight of a diamond is a very important parameter when it comes to
knowing its total price. Diamonds are always priced per carat.

diamond scale


The color of a diamond is graded with alphabetical letter (D to Z)

D is for the best and most lucid color and Z is for the lowest (yellow or brown).

Please note that the color of a diamond can be lower than Z, but those stones are called fancy colored diamonds to which I will refer in a difference paragraph.

I regard D to F graded diamonds as colorless.

diamond sort


Cut is a mark the diamond laboratories give according to the geometrical data of the stone, like the numbers of facets, the table and the total depth size in percentages, the angels of the facets, whether the diamond is perfectly rounded and how much the diamond sparkles (reflects the light back to your eyes).

The diamonds laboratories use the scale of Fair (the lowest grade), Good, Very Good and Excellent (the highest grade for Cut).

This scale grading mark by the diamond laboratories is also given to the polished facets and the symmetry of the diamond.

Please note that fancy shaped diamonds do not have the cut grading written on the certificate.


A diamond clarity grade refers to the inclusion in the diamond (black inclusion, white inclusion, cloud, and feather). The clarity scale goes from: FL (flawless), IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2. Very few laboratories include the grades SI3 and I3 in their reports as well.

moti check

Now that you understand the meaning of the 4 C’s you will find that it is not enough to just know the diamond language, if you still want to buy yourself a loose polished diamond in the worldwide diamond market.

Always stick to your budget.

Obviously before shopping for an engagement diamond ring you must think of a certain budget, otherwise you might get confused - there are small diamonds, there are big ones, there are diamonds of high color and of low color, there are clean diamonds and there are diamonds of low clarity, and of course – there is the combination of all these various parameters…

Which parameter is the most important?

After all, we are talking about your money, and with the same budget you can buy a one carat F VS2 or a one carat G VS1 (one lower grade color as opposed to one higher grade clarity).

For the same budget, you can buy a small diamond with a high color grade, or big diamond with a lower color grade…

You can play with the combinations of Carat, Color and Clarity, but when it comes to the diamond Cut, the grade different.

The Cut gives the diamond its glow, its brilliance, the reflection of the light that you can see when looking at the diamond.

This is the reason I believe the Cut is the most important parameter of the 4 C’s.

An excellent cut will always be better than a very good cut, and now you can understand why – what is a high color stone worth if it is not shining? After all, you are looking to buy a diamond for your engagement ring.

Which kind of diamond grading certificate can I trust?

Every jewelry store or diamond retailer can issue a certificate with the 4 C’s that have been mentioned.
Are they professional enough or honest enough to do so?

Many years ago, and even today, a lot of jewelry stores issue their own diamond certificates showing you the 4 C’s, with all of the diamond’s parameters on a chart.

Not all diamond retailers and jewelry stores have a gemologist with the appropriate education to do so, and besides, they might have an incentive to lie for their own sake, just think that they can show you a diamond that their certificate says, clarity VS1 instead of VS2, and you can't see or know the difference – and to you is it a lot of money.

Therefore, I suggest you buy your dream diamond only with an objective diamond-grading institute.

I recommend you buy loose polished diamonds only with a GIA certificate, which is known to be the most accurate and strict laboratory.

Do not be influenced by sellers offering you "a good price" for their diamonds, graded by their own people, and refuse even if they offer you a certificate from another unknown diamond institute.

Please feel free to contact us with any questions and requests.

It's  Definitely  Worthwhile  To  Contact Us –
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