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Guide to Diamonds – Everything you need to know

Know them well, it is simple?

You surely know the 4Cs (Cut, Color, Clarity, Carat), the 4 key parameters to determine the quality of a Diamond, we will definitely discuss and talk about them, mentioning them is necessary. You really think that knowing the 4Cs is enough to claim to know Diamonds ?
Many people ask us if a Diamond lasts forever, if and how can happen that it loses luster and how to keep it beautiful and shining over time.
Sometimes we are asked about the Diamond, often is taken for granted that everyone knows its nature and characteristics, but it’s not always so.

In this article we will cover the topics gradually, starting from basic knowledge, answering as far as possible the most common questions and curiosities, even mentioning and, if requested by our readers, deepening technical and scientific aspects on the subject, trying to avoid dwelling on too much.

The topic will be treated in the best possible way, with simplicity, taking advantage of the knowledge and support of Gemologists, Goldsmiths, Technicians and sales staff, who every day directly talk to and confront people and customers within our Company.
If you need more explanation or clarification on a particular topic, please contact us and we will do our best to satisfy you.

The Diamond

Among the most commercialized, known and desired stones, the Diamond has followed the history of man and his evolution, making him dream, adorning the most beautiful jewels of many famous Emperors and Rulers.
By now it is thought that everything is known about this wonderful stone, always regarded as the king of all precious gems.

Diamond’s 4Cs (Cut, Color, Clarity, Carat):


The key factor to get the maximum shine and brightness from a gem, it’s a determinant factor for a Diamond and for any other gem in general.
The most used and widespread cut is the Round Brilliant cut, so you should correctly talk about: Round Brilliant, Oval, Pear-Drop, Navette-Marquise, Princess, Radiant, Heart, Cushion, Trilliant diamond cuts; Step cuts such as Emerald cuts, both square and rectangular, and other mixed and fantasy cuts. Commercially, the most used and popular are the Round Brilliant cut Diamonds (as already mentioned).
This type of cut consists of 57/58 facets in total, 32 + 1 on the top (crown), 24 on the lower half (pavilion) + 1 extra if the apex is multifaceted. Very often people tend to shorten terms they use very much, so frequently we hear talking about Brilliants, using such a term to indicate the Round Brilliant cut Diamonds, but this would not be correct, as the Round Brilliant cut can be applied to other gems, precious and not.
The modern brilliant cut, as we conceive it today, was created in 1919 by Tolkowsky; although this is not the only version of modern cuts, it is certainly the starting and reference point in the modern brilliant cut Era. Today in many countries the most important Brands use Diamonds cut with very good proportions, thus ensuring high quality standards; but this does not preclude the fact that on the market there are diamonds cut with mediocre or poor proportions (less and less frequently over the years).
It is also true the opposite, that in recent years, with the development of more advanced technological factors, diamond cuts have been designed and made with absolute precision, achieving a brightness never seen before. Generally, they are not commonly mounted in normal jewelry, as these excellent cuts produce a greater waste from the rough Diamond in the cutting process and so, raising the Diamond’s price per carat, they can generate an average increase between 10% and 20% compared to similar stones.
We must point out that usually these excellent cuts applied to diamonds are especially appreciable on stones that have a minimum size, the bigger they are the more you can appreciate the difference between Optimal and Excellent cuts.


The Diamond reference Color Scale is often misunderstood by most nonprofessionals, this chart clearly illustrates the grading of diamond’s Whites. In fact, it’s a series of shades of white and not of real differences between Diamonds’ colors, and it’s dedicated exclusively to “colorless / white” diamonds and it’s absolutely not used for Fancy Color Diamonds, whose colors are: Yellow, Pink, Brown, Black, Green, Light Blue/Blue, Red. This generates among most customers the mistaken belief that one single degree of color difference between one diamond and another is easily visible to the naked eye in mounted jewelry.

That’s not true. In fact, a mounted Diamond is also submitted to the reflection of the adjacent metal, and this often makes impossible to see differences between 1-2 color grades (it also depends on the sensitivity of the eye). Obviously, we are talking about very small differences that will certainly increase or decrease the value and preciousness of a Diamond, but not so noticeably as you might think. Some people, to better understand the whites scale used for diamonds, give the example of a jug of water to which is added one drop of color at a time, every drop representing in an illustrative way 1 degree of color, so we are talking about very small differences.
As you can see from the picture, the Diamond Color Scale goes from the letter D to Z, where D is totally colorless and Z is yellowish-sallow (but not yellow); when the intensity of color goes beyond grade Z we talk about Fancy Color Diamonds. Until today, almost 300 different colors have been classified. Commercially, the selection most used for diamonds mounted in Golden or Platinum jewelry by important Brands is between colors F and H; this does not preclude the possibility of using other shades of white.


This point deserves important clarifications, it’s not enough to say that this Diamond Scale indicates which Gems are more or less pure or beautiful. You will see that in Italian the word “purity” (purezza) is commonly used, as the exact translation of clarity (chiarezza) does not describe the concept well in our language.

Essential point: we are not talking about purities or impurities, but about natural inclusions inside the crystals of a Diamond. In these crystals, during the formation and growth phase, it happens that very small extraneous elements get trapped within their structure: these internal inclusions are considered as if they were “fingerprints” of the Diamond, making it unique; therefore is correct to talk about characteristics of diamonds and not defects.

These natural internal inclusions, if they are small, absolutely do not affect the beauty of a diamond, unless they become evident to the eye. In fact, the correct classification is determined by professionals (Gemologists) who do the evaluation and analysis with the help of a lens or a microscope at 10 X (10 magnifications), so up to the rank of “Purity” SI2 the eye should not see anything at all, if properly classified. Many Brands use Clarities ranging from IF to SI2, not just for commercial factors, in order to propose, in addition to Diamond internally pure (IF), also diamonds with some inclusions (VVS, VS, SI) that could help lower the prices, without penalizing the overall beauty of the gems.
Clarity classification of a Diamond:
  • FL (internally and externally pure with 10 X lens); only used on some gemological laboratories and not by all.
  • IF (internally pure with 10 X lens).
  • VVS1, VVS2 (very, very small inclusions, hardly visible with 10 X lens).
  • VS1, VS2 (very small inclusions, barely visible with 10 X lens).
  • SI1, SI2, SI3 (small inclusions visible with 10 X lens); PS: the SI3 degree is not used and recognized by many important gemological institutes and laboratories.
  • I1 (inclusions hard to see with the naked eye), I2 (inclusions visible to the naked eye), I3 (inclusions easily visible to the naked eye).
  • Carat

    It’s the unit of measure (mass) used to weigh all precious stones, including diamonds, of course; from now on referred to by the initials ct.

    1 ct. corresponds to 1/5 of a gram, so 5 ct. correspond to 1 gram.

    The subunit of ct. is the “point”, a hundredth of a ct., so all diamonds weighing less than 1 ct. may have their weight expressed in “points”, e.g. a Diamond of 20 points = 0.20 ct.; the indication in ct. remains by far the most used and correct.

    There are also other subunits that haven’t been used for several years, so we will not take them into account. The word Carat has its origin in the fact that once, when there was no appropriate equipment, the seeds of Carob were used to weigh Diamonds.

    These seeds have the property to have a surprisingly regular weight, so at the time they were an ideal method to weigh Diamonds and other precious gems.

    Cleaning and maintenance

    We are often asked about how to clean jewelry with Diamonds, and the spontaneous response is: turn to your trusted jeweler who, in a short time and with professional tools, will provide a thorough cleaning of the jewels, performed by an expert goldsmith. Anyway, I have prepared an article in which I describe how you can easily clean them at home, by yourself. This type of operation done by a professional can still be useful to check the jewels, because they may need some repair or maintenance intervention necessary to restore those that show signs of wear. These operations don’t always require high expenses and sometimes even with partial actions you can keep your jewelry in good condition.
    You have to know that grease adheres easily to a Diamond, so if you wear your jewelry even when you do jobs involving direct contact with this item (grease), the Diamond will easily tend to lose (temporarily) its natural brightness. But don’t worry, after a good cleaning it will return as bright and beautiful as before.
    Some of you have asked if we could give more information on this topic, so we dedicated an article exclusively to: how to clean jewelry.

    Features of Diamonds

    Let’s see less known but still important parameters that determine the quality of Diamonds, such as Fluorescence, proportions of Cut, Polish, Symmetry but also size and polish of Girdle and Culet.


    This is the reaction that some Diamonds can have under a long-wave Ultraviolet light (366 nm), about 50% of Diamonds feature a blue-toned reaction (but not only), see the example in the picture, the same Diamond in natural light on the left and on the right subjected to UV light; It is a completely natural factor, which generally does not affect the beauty and preciousness of Diamonds, except in cases where the fluorescence appears to be medium or strong.
    This type of testing is always applied to Diamonds with a Gemmological Certificate, an analysis that is not always carried out during a Gemmological test, as this is only to check the main features. Fluorescence is a temporary phenomenon, as soon as the UV light source is turned off, the effect of Fluorescence in Diamonds disappears.
    Fluorescence in Diamonds is classified on average in 4 different degrees, some Gemmological Institutes use 7 degrees:
    • None
    • Faint
    • Medium
    • Strong

    Proportions (Cut, Polish, Symmetry)

    These are parameters closely linked to the quality of the cut (as already mentioned), what is mentioned is the quality of the general proportions of the Cut, the Finishing and Polish of the facets, 3 parameters (which in some Certificates are grouped into 2); in some cases, some certification bodies use Ideal or Excellent considering them as equal classifications. The higher the quality and precision of the cut, the greater the brilliance and luminosity of the Diamonds, the importance of this feature is clear but it grows, as the size of the Diamond in question grows.
    The Proportions of Cut, Polish, and Symmetry are classified into:
    • Excellent – Ideal
    • Very Good
    • Good
    • Fair
    • Poor


    It can have variable thickness depending on the choice of the Diamond cutter, ranging from: Very Thin, Thin, Medium, Thick, Very Thick. Normally most of the Diamonds are cut with a thin or medium girdle, one tends a very thin girdle to avoid problems in the setting phase, and very thick to avoid aesthetic deterioration. The Diamond Girdle is often Frosted, leaving it dull (as preferred by many), alternatively sometimes it can be Faceted or Polished, this does not increase or decrease the quality of it or value, it is simply an aesthetic or practical choice on the part of the Diamond cutter.
    The thickness of the Girdle is classified using 5 to 7 degrees, depending on the Gemmological Institute:
    • Very Thin
    • Thin
    • Medium
    • Thick
    • Very Thick


    It is the point located on the lower part (canopy), in Diamonds it can be pointy or faceted, even in this case it generally does not change the quality, except when (rare cases) the facet is too large and evident.
    The Culet is classified according to 5 degrees but sometimes 7 may be used:
    • Pointed
    • Very Thin
    • Thin
    • Medium
    • Thick
    • Very Thick


    The features, that go beyond the “classic” 4 Cs, are not normally checked during simple “tests”, in Jewellery from normal production, even to reduce costs, as when it comes to small stones, they would have a great influence on the price. The research of these additional features requires a thorough and accurate “gemmological testing”, after which a “Gemmological certificate” is issued, considered by many like an “ID card” for Diamonds, which reports and describes all identifiable features of the gem in question. Generally Diamonds used in commercial Jewellery are accompanied by a “warranty” or better defined as an “authenticity certificate” which states the general characteristics of the Jewel you are buying, while for more important Jewels or customized pieces made by professionals a “gemmological certificate” is often preferred. This is a personal commercial choice on the part of the seller, there are no requirements at this time which call for something beyond normal documentation.
    Gemmological certificates are issued by independent gemmological laboratories, scattered around the world, many but not all equally accurate and reliable, ask for advice from serious professionals (preferably gemmologists), who can give you further information regarding the most reliable certifications on the market.

    Physical and Chemical Features of Diamonds

    Hardness: 10 on the Mohs scale
    A small clarification not known by all, the Mohs scale, among the most used and mentioned is a relative scale ranging from 1 to 10, where 1 is the most tender natural material ever and 10 is the hardest natural material ever, but the hardness proportions are not exactly equidistant and proportional. Let’s consider our case, Diamonds grade 10 Mohs and Corundum grade 9 Mohs, we could think that Diamonds are harder than Corundum by 1/10 but it is not so; Diamonds are 140 times harder than Corundum, indeed one should refer to the Vickers scale where hardness is measured not on a relative scale, but on an effective one, thus making it more accurate in the difference between the hardness of the various materials, but this is not easy to understand and it is not apt for quick comparison for everyday use, so many keep on using the Mohs scale for ease of use.
    Practical example, hardness of Diamonds and Corundum on the Mohs and Vickers scales:
                        Mohs          Vickers
    Diamond:      10             8400
    Corundum:     9              2000
    Density:       3,50/3,55
    Breakage: easy, parallel to the octahedron faces.
    Not to worry, practically, in everyday life, it is very difficult for this to happen, the hit that might cause damage must be precise and targeted at the right angle, it is definitely not impossible to break Diamonds, but it seldom happens.
    • Crystal: (cubic system), octahedron, cube, rhombic dodecahedron.Chemical element: C (carbon).
    • Transparency: from transparent to opaque.
    • Fluorescence: very variable.

    Diamonds Mines

    The main diamond mines in the world are found in Africa, Australia, Russia, Canada, China, Brazil, Venezuela and other small and less important mines. One could mention who the major manufacturers are today, but suffice it to say that those listed are likely to remain the main ones, in fact it is impossible to know or predict when new mines will be discovered and what extractive quantity and quality they might feature. The smaller mines reach a yield of 0.20 ct for each ton of rock extracted, up to the most profitable deposits with yield 7 ct. per ton.

    Diamond Imitations

    Man has always tried to imitate and copy mother nature, even in this case there is no exception. There are many imitations of various type and genre, “poor” imitations that are hard to mistake for Diamonds and others that are more difficult to spot.
    The most well-known are:
    Leaded glass (Rhinestones), GGG (Galliant), Lithium Niobate (Linobate), strontium titanate (Fabulite, Diagem), YAG (Diamonair, Cirolite), cubic Zirconia (Dievalite, Phianite, phianites) commonly (and incorrectly) called zircon, synthetic Moissanite, synthetic Diamond.
    Anyone wishing to know more about this topic can see the article Synthetic and Artificial Gems.
    There are also Natural gems that have been used as imitations for diamonds, these are: Beryl, Cerussite, Corundum, Crystal Quartz, Scheelite, Sphalerite, Topaz, Zirconia.
    Few of these Artificial or Synthetic Gems are used today and spread on the market and can be considered as imitations of Diamonds, commonly the most widespread are:
    Glass Lead: commonly called “Rhinestone,” very widespread in Metal and Silver costume Jewellery (a poor imitation and easily recognizable).
    Cubic Zirconia: mistakenly called “Zircon”, why mistakenly?, because there is a Natural stone that is called Zirconia and that has nothing to do with cubic Zirconia (cheap and recognizable imitation).
    Synthetic Moissanite: simply called Moissanite, this gem appeared a few years ago on the Jewellery market,  it seems to be the best imitation of Diamonds as it has very similar characteristics, it is not recognizable for ordinary people and for some sellers but it can be identified without great difficulty by Gemmologists.
    Synthetic Diamond: this is definitely the most complex synthetic gemstone to identify even for Gemmologists that are not equipped with sophisticated tools, present only in large laboratories. These stones are Diamonds in all respects, so it takes complex tests to identify them. Nevertheless the topic does not currently pose particular concern as the cost to produce synthetic diamonds is equal if not greater to the costs to extract natural ones.

    Sophistication and treatments of Diamonds

    Some of you might wonder if there are beautification treatments made on Diamonds.
    Well yes, but you do not have to worry, you can read more about it at the end of the article on Artificial and Synthetic Gems, where the topic is discussed.
    However remember, buying Trademarks / Brands and on secure channels provides safety in your purchase.

    How Diamonds are born

    Diamond crystals were formed millions of years ago at hundreds of kilometres below the Earth’s surface, where high temperatures and high pressure transformed simple Carbon in Diamonds crystals (a crystallization of pure Carbon), then through an incredible and long journey, they emerged on the surface of the Earth through the eruption of volcanoes, which spread the Diamond crystals over hundreds of kilometres.

    Diamonds have in fact been found in various places, from the typical mine found on the former crater of old volcanoes, alluvial deposits along rivers or beaches, and in some cases even on the seabed.

    Currently the main sites of extraction are in: Africa, the Americas, Australia, Russia, Asia.
    The word Diamond comes from the ancient Greek “adamas”, invincible, indomitable, incorruptible.
    From historical records we trace the appearance of Diamonds back to about 2800 years ago, some think that their appearance is even older, but there are no historical record that prove it.
    Initially used exclusively by powerful men who wanted to show their status symbol and power.
    They adorned jewels, crowns, sceptres and other ornamental objects, often worn by the most powerful and famous Emperors and Kings. Until a few years ago exclusive privilege of the powerful and influential people on the world stage; today instead they are luckily worn and appreciated by the public at large.

    Famous Diamonds

    Below we will list essential data regarding the most famous Diamonds mankind has found and cut.
    • Sancy   ct. 55 found in 1470.
    • Florence (Tuscany)  ct. 137.27 in 1657 It was owned by the Medici family of Florence, donated in 18th century to the Habsburg Crown, currently we ignore those who neither hold.
    • Dresda   ct. 41 found in 1742.
    • Koh-i-noor   ct. 108.93 found in 1739 a gem cut round previously.
    • Scià (Shah)   ct. 88.70 donated in 1829.
    • Hope   ct. 45.52 found in 1830.
    • Tiffany   ct. 128.51 found in 1878.
    • Cullinan 1 (Star of Africa)   ct. 530.20 found in 1908 , This is the main bud along with other 104 from a rough ct. 3106 .
    • Cullinan 2   ct. 317.40 .
    • Cullinan 4   ct. 63.60 found in 1908 , one of 105 stones taken from Cullinan.
    • Nassak (Eye of the idol)   ct. 43.38 obtained from a previous gem of ct. 90 and cropped in 1927.
    • Centenary   ct. 273 .
    • De Beers   ct. 234.50 .
    • Gran Mogol   ct. 787.50 .
    • Woyie River   ct. 770 .
    • President Vargas   ct. 726.60 .
    • Jonker   ct. 726.60 .
    • Jubilee (Reitz)   ct. 650.80 .
    • Nizan   ct. 277 .
    • Orlow   ct. 189.60 .
    • Regent (Pitt)   ct. 140.50 .
    • Victoria   ct. 228.50 .

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