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Diamonds are beautiful, hard, enduring, expensive and rare, right?  Actually, diamonds are not rare;  they are mined all over the world.  Until very recently, the diamond market was so tightly controlled that prices were kept artificially high.  The Internet has opened markets previously inaccessible to consumers, and, armed with the right information, the savvy shopper stands to save a lot of money whether shopping online or in a traditional jewellery store.

The Perfect Diamond

D Flawless, 1 carat, round brilliant, ideal cut...the perfect diamond.  Technically, maybe, but after some consideration, you may decide your perfect diamond is something quite different.

Diamond Proportions

The Famous 4 Cs

When people think of diamonds, they usually think of the 4 Cs:  Cut, Colour, Clarity and Carat weight.


It is the cut of the diamond that determines how brilliant the diamond will be; not colour, not clarity and not carat weight.  A quality cut turns a mere rock into a sparkling gem.

The term cut actually refers to the number and arrangement of the facets in a gem, while shape refers to a gemstone's overall outline.  The traditional shape and cut of a diamond is the round brilliant.  Anything else is generally considered a "fancy" cut.

Some Popular Diamond Shapes
Diamond Shapes

Unfortunately, most diamonds are not well cut. D Flawless diamonds are often poorly cut to retain maximum carat weight and therefore sparkle less than well cut lower quality diamonds. The surprising truth is there is no universally accepted standard for what a properly cut diamond should look like.

The goal of a diamond cut is to achieve maximum light return with minimum light leakage.  In other words, in a perfect world, all the light that enters the top of the diamond would be reflected across the stone and bounced back out the top.  This light return is called brilliance, and the De Beers company has added brilliance to the 4 Cs as a new standard for diamond grading.  It's not really new, though, because, as already stated, brilliance is a result of the cut.

If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion, creating a reflection of the girdle in the center called a "fish eye" or a dark area called a "nail head."  If the cut is too shallow, light escapes through the pavilion before it can be reflected.

Diamond Cut

Mathematician and physicist Marcel Tolkowsky, a member of a family of Belgian diamond cutters, was the first to present a mathematical and optical analysis of diamond cut.  Published in 1919 in London and New York, Tolkowsky's Diamond Design changed the diamond cutting industry.  The proportions for Tolkowsky's "Ideal" cut were mathematically calculated for maximum brilliance, and it is the forerunner of the modern round brilliant.  The Tolkowsky family continues its tradition of fine diamond cutting today with its "Cut by Tolkowsky* The World's Original Ideal Cut Diamond" brand.

The cutting industry lacked the technology to achieve Tolkowsky's ideal proportions in the early 20th century, but as skill and technology improved, cuts came closer and closer.  In 1945, the term Ideal Cut was trademarked by the American Gem Society to represent its highest quality cut grade.  However, the term "ideal cut" gets tossed about by many marketers and applied to a wide range of cuts that would never meet the AGS Ideal Cut standards, or Marcel Tolkowsky's original parameters.

In 2005, the Gemological Institute of America introduced a cut grading system for round brilliant diamonds in the D to Z colour range.  It assigns an overall cut grade ranging from Excellent to Poor.  Most labs and appraisers use a similar system to describe cut quality.  The difference is that there is no industry organization which sets the standards that define the terms, so one lab's "Very Good" cut grade could be another's "Excellent" unless both are using the same cut grading standards.  Even if they are using the same standards, there always will be some discrepancies simply because of the human factor.  Ultimately, all diamond and gemstone grading is somewhat subjective.


Colourless diamonds (also sometimes referred to as "white" diamonds) are graded by letters D-Z, with D being colourless and each letter having an increasingly yellow tint.  Loose diamonds are graded upside down against a Master Colour Set under controlled lighting.  Mounted diamonds cannot be graded properly and therefore any colour grade assigned to a diamond after mounting should be considered approximate.

Diamond Colour

Grades D-E-F are known as the colourless grades. The colour grade of D is reserved for diamonds over .50 ct, whose colours can be more accurately graded. Diamonds less than .50 carat usually will get a top grade of F because it is more difficult to grade a small diamond to the exact color grade.  Diamonds in this colour range are excellent for setting in white metal.

Grades G-H-I are considered to face up white or face up colourless grades. These diamonds appear colourless through the face up position, which is how they are viewed when set in a ring, but when turned upside down for proper grading they will show a slight tint of colour.

Grades J-K-L have a slight tint, but still appear mostly colorless when well cut and proportioned.  It is easier to see the colour of a diamond in a white setting, so consider setting diamonds in this colour range in yellow gold.  These can be truly beautiful diamonds and can offer the consumer a larger diamond than a similarly cut stone of a higher color grade.

Grades M-Z have a continuously increasing amount of yellow tint and are generally considered "off" colours because they do not have enough colour to be considered "fancy yellow."


After carat weight, clarity has the biggest impact on diamond prices. Diamonds are graded using a 10X loupe.

Diamond Clarity

No inclusions visible by an expert at 10X magnification.
VVS1-VVS2  Very, very slight inclusions that are very difficult for an expert to find under 10X.
VS1-VS2 Very slight inclusions that are difficult for an expert to find under 10X.
SI1-SI2  Noticeable inclusions that are relatively easy to find under 10X, but not visible without magnification in a face up direction.
I1-I3  Obvious inclusions under 10X that may be visible to the unaided eye and affect the beauty or durability of the stone. I3 inclusions affect both the stone's beauty and durability.

Flawless diamonds are rare, and their prices reflect that fact.  However, even experts cannot tell the difference between a flawless and SI1 diamond without a loupe, and therefore, all grades SI2 and above are considered "eye clean."

Be on the lookout for clarity enhanced diamonds, which are described in the Treatments section below.

Carat Weight

Carat weight is the simplest and only truly objective of the 4 Cs, and has the greatest effect on price.  One carat is divided into 100 "points," so a diamond of 75 points weighs 0.75 carats.  If carat weight is truly objective, then how is it possible for two diamonds of equal weight to be different sizes?  It has to do with spread, or how the weight is distributed within the cut.  Spread determines how much of the diamond faces up.  A thick girdle or a deep pavilion can push a diamond up to that next "magic" weight (and price) level but have no visual impact, and actually can detract from a diamond's overall beauty and value.

Diamond weight in set jewelry is often listed as total carat weight or ctw.  Be aware, however, that the value of a 2 ctw diamond piece is very different from that of a 2 ct diamond.


There are a variety of enhancements or treatments that can significantly alter the appearance of a diamond. The FTC requires all diamond treatments be disclosed to consumers. Failure to do so can result in fraud charges and lawsuits against the diamond dealer.

A treated diamond should not command the same price as a natural untreated one, which can allow a consumer to purchase a larger diamond for less money.  However, if you know you do not want a treated diamond, specifically ask for a non-treated or unenhanced diamond only, and have the merchant clearly indicate on the invoice that the diamond is in fact 100% natural and untreated.

Fracture filling with a substance of the same density as the diamond makes surface reaching fractures seem to disappear, much like the process used to repair cracked windshields.  A chemical added to the filling creates a "neon flash" effect that makes the filling visible under magnification.  Fracture filling is not a permanent treatment, as the filling will break down over time.

Laser drilling literally burns out dark inclusions in a diamond, typically leaving white lines that are visible under side-view magnification, and resembling a tiny white dot when viewed from the top.  Laser drilling is a permanent treatment.  Sometimes the drill holes are then filled, which makes them more difficult to see, but the filling is not a permanent treatment.

HPHT (high pressure/high temperature) treatment works in a couple of different ways.  In certain types of diamonds, HPHT can turn an off colour diamond into an intense yellow.  In other types of diamonds, it can improve an off brown to almost colourless.  HPHT treatment is difficult to detect.

is the use of neutrons, gamma rays or beta particles (high energy electrons) to alter a diamond’s colour.  Almost all fancy colored diamonds on the market today have been irradiated to intensify their colour.  Irradiated diamonds are susceptible to fading.

is being used to create fancy coloured diamonds, especially the light to fancy intense pinks.  Often these diamonds are only coated on the pavilion, and the coating can be scratched.

Fancy Coloured Diamonds

Fancy coloured diamonds, especially natural fancy colours, are rare.  Only 0.01% of natural diamonds are fancy colours.  The majority of fancy coloured diamonds on the market have been irradiated to improve their colour and are priced significantly less than natural untreated diamonds.  The exception is brown diamonds, which are not treated.  They range in colour from light champagne (C1) to cognac (C7).

Synthetics & Simulants

A synthetic diamond, by definition, is chemically, physically and optically identical to its natural counterpart, but it is manufactured in a laboratory.  Synthetic diamonds have been manufactured by various processes for industrial use for more than half a century. However, in recent years gem-quality synthetic diamonds have come on the market.  The majority of  synthetic diamonds are yellow, a result of nitrogen impurities in the crystal. Other colours such as blue, green or pink may be produced by the addition of boron or from irradiation after synthesis.  There has been less success in synthesizing colorless diamonds.

A simulant can be any non-diamond material that has the appearance of a diamond and is used as a substitute.  The most popular diamond simulants are cubic zirconia and synthetic moissanite, both of which are man-made.  There are other natural stones that serve well as lower-cost diamond substitutes, including colorless sapphire and zircon.

"Certified" Diamonds

Many diamonds are sold as certified diamonds, which actually means that they have been professionally graded and issued a "cert," or grading report.  Not all certificates are created equal, because not all laboratories grade by the same standards.  You should make sure that any documentation that comes with your diamond is from a reputable independent grading lab.

Appraised Values

"Certs" or grading reports should not include a monetary valuation.  Valuation is the job of the gemmologist appraiser, who is trained to look at a piece of jewellery or loose stone and assess its quality and value.  If your diamond comes with an appraisal, it should be from an independent appraiser and not an in-house appraiser.  It should also specify the type of valuation, i.e. Insurance Replacement, Estimated Retail, or Fair Market Value.

Conflict Diamonds

Conflict diamonds, also known as ‘blood’ diamonds, are rough diamonds used by rebel movements or their allies to finance armed conflicts aimed at undermining legitimate governments.  The Kimberley Process is an international initiative that requires international shipments of rough diamonds be accompanied by a Kimberley Process certificate guaranteeing that they are conflict-free.  According to the Kimberley Process official web site, diamond experts estimate that conflict diamonds now represent a fraction of one percent of the international trade in diamonds, compared to estimates of up to 15% in the 1990s.

-By Cynthia B. Reuschel RGA

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