Diamond Guide

Education: Diamonds

Diamonds are the hardest of all gems and therefore can be polished to exquisite brilliance and can, under normal care, last a lifetime. When we think of diamonds, we often relate them to the name DeBeers. The DeBeers name has been associated with diamonds since their modern day discovery. The company, based in South Africa with headquarters in London, quickly became the largest distributor of diamonds and soon thereafter was considered a monopoly, controlling more than 80% of the world supply of diamonds. A distribution method was set up whereby "sightholders" were invited to buy boxes of diamond rough. This division of DeBeers is known as the DTC or Diamond Trading Company.

The way the system works is that these sightholders (clients) are invited to buy diamond rough usually ten times per year. They do not get to view the diamond rough prior to purchasing. The boxes are sealed and the buyers do not know what the mix will be like. The DTC has a good idea what sizes and qualities the buyer needs so they do try to offer that selection. However, the price is set and non-negotiable. When the DTC decides to raise prices, the sightholders have to accept the new price. While this system seems unfair, it did work well overall and this method of distribution helped create even greater demand for diamonds worldwide. People knew that diamond prices would continue to rise over time because of this control. The DTC controlled the supply and the price of diamonds.

Over time, more large scale mining companies entered the diamond business. The market share of DeBeers began to decline. However, due to rising demand worldwide, DeBeers sales did not suffer. The sightholder method of distribution remained but was restructured. Many of these invited companies were no longer in this group which is now called Supplier of Choice instead of sightholder. DeBeers wanted this restructuring for many reasons including better marketing efforts by all diamond companies and shared responsibility. They also wanted to eliminate their monopoly status that had kept them from certain business practices in the United States. The market share of DeBeers is now below 50%.

Rarity and Value

Even though new diamond exploration, including in Canada, has greatly added to the supply, the diamonds produced are continually bought up. Periodically, the industry will experience shortages of certain sizes, shapes, or qualities. As diamonds get larger, they are rarer and therefore more valuable. Two diamonds of say one half carat each of a particular color and clarity will cost considerably less than one diamond of one carat even though they both have the same total weight. The diamond grading scale is also factor in rarity and value. Diamonds of very high color and clarity are much more rare than diamonds of lower color and clarity. Therefore, the price can be astoundingly different for two diamonds that are the same size but have differences in quality grades.


When you are planning on purchasing a diamond it is important that you know as much as possible about how diamonds are classified.Diamonds are available in varying colours, sizes and qualities. They naturally occur in colours ranging from very clear fine whites to pinks, bright yellows, greens and browns, though the majority of diamonds used in jewellery today are white diamonds.

At least 13 factors affect the value of a white diamond, including fluorescence, table percentage, symmetry and other crucial details. The 4 Cs are just a good place to start - Colour, Clarity, Cut and Carat Weight.


While many diamonds appear colourless, or white, they may actually have subtle yellow or brown tones that can be detected when comparing diamonds side by side. Diamonds were formed under intense heat and pressure, and traces of other elements may have been incorporated into their atomic structure accounting for the variances in colour. The scale for grading ranges from D which is totally colourless, to Z which is a pale yellow or brown colour. Diamonds that are ‘colourless’ (graded D, E or F) are very rare and demand premium prices. The untrained eye will find it very difficult to distinguish between D, E or F grades. G, H, I and J are ‘near colourless’ and represent excellent value for money. G and H are sometimes called ‘rare white’ and are the most sought after in the ‘near colourless’ group.


Clarity is the term used to describe the size and number of inclusions in a diamond. Almost all diamonds contain minute traces of non-crystallised carbon, the element from which they were born. These inclusions are nature's finger print and make every diamond quite unique. Most are not discernible to the naked eye and require magnification to become apparent. Large inclusions interfere with the dispersion of light and therefore the diamond's brilliance. The larger or more numerous the inclusions the less valuable the diamond. The fewer the inclusions, the rarer the stone. Each diamond will have its own unique inclusions in various positions within the diamond. VVs, Vs and Si inclusions are not visible to the naked eye; they are only visible through magnification.FL = Flawless -- no internal or external inclusions of any kind visible under 10x magnification to a trained eye, the most rare and expensive of all clarity grades

IF = Internally Flawless - no internal inclusions visible under 10x magnification to a trained eye, but there may be some tiny external irregularities in the finish

VVS-1 = Very Very Slightly Included 2 -- tiny inclusions visible only to a trained eye under 10x magnification

VS-1 = Very Slightly Included 1 -- very small inclusions visible with 10x magnification

VS-2 = Very Slightly Included 2 -- several very small inclusions visible with 10x magnification

SI-1 = Slightly Included 1 -- small inclusions visible with 10x magnification

SI-2 = Slightly Included 2 -- several small inclusions visible with 10x magnification

I-1 = Included 1 -- flaws that are visible to the naked eye

I-2 = Included 2 -- many flaws clearly visible to the naked eye that also decrease the brilliance

I-3 = Included 3 -- many flaws clearly visible to the naked eye which decrease the brilliance and compromise the structure of the diamond, making it more easily cracked or chipped.


The cut of a diamond pertains both to the shape (round, marquise, princess, etc.), and to the make (how well it is cut for proportion and finish). The cut gives each diamond its unique sparkle and brilliance by allowing the maximum amount of light to enter and reflect back out of the diamond. While nature determines a diamond's colour, clarity and carat weight, the cut and make are the only factors in diamond grading that are controlled by human hands.

The major diamond shapes are:


The cut or make of a diamond is VERY important. If your diamond is too shallow, the sunlight will escape out of the bottom. If your diamond is too deep, it will escape out of the side. A diamond cut to proper proportion allows the greatest amount of light to be reflected, for maximum brilliance.

Diamond proportions have evolved over the last 100 years to increase the brilliance, scintillation and fire to dazzle the eye. Many details must be precisely managed and executed to create a truly beautiful diamond of excellent make.


Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip.

Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a hundredth of a carat.

Do not confuse carat with karat. Carat refers to stone weight while karat refers to fineness of gold.

Diamond Fluorescence

Roughly one is four diamonds will fluorescene to some degree. This is not necessarily something to be too concerned about unless it affects the stones face up look to such a degree that it appears “milky” in the daylight. Individual stones should always be judged on their own merits. In my top areas that concern me when buying diamonds this is my least important factor. And in some cases it can actually help a stones appearance if it is drawing yellow.

Diamond Treatments and Synthetics

Detecting diamond treatments and synthetic diamonds are a challenge to the entire industry. Some diamonds treatments are more challenging than others to identify. Here are the main diamond treatments and synthetics to know about.


Synthetic diamonds are identical to natural diamonds in their chemical characteristics. Methods to identify these exist and while they can be challenging and sometimes require expensive equipment, they are not thought to be a significant threat. However, very small diamonds that are set into jewelry can be much more difficult to determine their origin. Several diamond imitations, most notably cubic zirconia and synthetic moissanite, also exist. Neither of these poses great challenges in identification for an experienced jeweler or gemologist.


When diamonds have black inclusions, they may not be very appealing to the eye. A process for removing these black inclusions developed in the 1960s and had widespread use by the 1970s. First, the laser is focused on an inclusion and a microscopic drill hole is left behind. This allows an acid bath to enter the diamond and remove the black imperfections. Although this is done in an effort to improve the appearance of the diamond, one can debate whether it really does since it leaves a drill hole and white inclusion where there used to be a black inclusion. Most laser drilling is easy to identify. However, some newer methods are more challenging since they do not leave a drill hole. Pricing is erratic. Some will lower the price of the diamond due to the drilling process, while others will not, arguing that the diamond may still have the same clarity grade but with slightly improved appearance. The important thing here is disclosure. In the U.S., it is required to disclose all diamond treatments. As long as consumers know what has been done, it is then up to them to make an informed buying decision.


HTHP is the abbreviation for “High Temperature, High Pressure”. This treatment was perfected in the early 2000s for changing the color of a diamond using nothing more than controlled heating combined with high pressure. These expensive presses are effective on some diamonds and can change the color from a low yellowish or brownish color all the way up to D, E, or F colorless. The same process can also be used to change some diamonds into fancy color diamonds such as intense yellow or other colors. Detecting this treatment is the most challenging in the industry. Sometimes, microscopic signs are left behind that can be proof positive of the treatment. But other times, there are no signs. Sophisticated equipment can act as screeners for these treatments.


Irradiation of a diamond is used strictly to create fancy color diamonds from off-color inexpensive diamonds. The process is controlled and stable. Resulting colors can be a wide range including green, yellow, orange, pink, and even red. Some irradiated diamonds are relatively easy to detect with simple tests and magnification while some require more extensive testing and equipment.


Clarity Enhancement is a process involving the use of a lead-based glass that through heating and pressure, is imparted into the diamond, effectively hiding the feathery type of inclusions. The film-like layer of glass is so fine and minute that it does not add significant weight (if any at all) to the diamond. The process is very effective in masking these inclusions. The correct term for this treatment is clarity enhanced, though many in the trade prefer to use the term “fracture-filled”. Diamonds do not have fractures that are being filled; they are cleavages (feathers), and gemologically speaking, there is a difference. As long as the treatment is properly disclosed, it again is up to educated consumers to decide if this product is for them.

It also is important to note that the treatment may not be stable. Care should be taken with these diamonds. They should not be placed in an ultrasonic cleaner. If repairs are to be done by a jeweler, the jeweler should be informed about the treatment as the high heat generated by a jeweler’s torch would damage the filler. It can be retreated if this should happen.