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Diamond Education




This is easily the most popular of all diamond shapes, accounting for at least 75 percent of all diamond sales worldwide. Fortunately, diamond cutters have been studying the balance of light within the round diamond for more than 100 years and it has come down to a precise science and mathematical application. Not all round diamonds are brilliants, which is technically described as a round with 58 facets.



After round brilliants, the princess cut is the next most popular diamond shape, especially for engagement and wedding rings. The ideal princess cut diamond is near square, with a width to length ratio of between 1.0 and 1.05, while rectangular princess cuts can have a ratio of greater than 1.10. Princess cut diamonds are exceptionally brilliant and pleasing to the eye.



The emerald cut is characterized by an open plane and side cuts that resemble stair steps or a pyramid. The emerald cut typically has a length to width ratio of 1.30 to 1.40. Because of its wide plane, the emerald cut is best for coloured diamonds or best-clarity stones, as any imperfections will be apparent.



What happens when you cross round, emerald and princess diamonds? You get a radiant cut, typically square in shape with lots of rounded edges. Radiant cut diamonds look fabulous with adjacent baguettes or rounds. Length-to-width ratios for square radiants are usually 1.0 to 1.05 and 1.10 for a more rectangular shape.



The oval cut is similar to the round brilliant, only it has a much more elongated body. This cut accentuates brilliance and carat weight and can make fingers look long and graceful. It is also ideally suited for accent gemstones. Generally, length-to-width ratios of oval diamonds fall between 1.33 and 1.66.



The pear cut is often referred to as a teardrop, as it has one rounded end and one pointed. This is a brilliant cut, meaning it has exactly 58 facets, and its shape lends well to pendants and drop earrings. Traditional pear-shaped diamonds have length-to-width ratios of between 1.45 and 1.75.



Marquise-cut diamonds date back to Louis XIV of France, the so-called "Sun-King," and have pointed ends with an elongated middle. The long shape maximizes carat weight and has the visual effect of lengthening the finger. This shape also looks spectacular with side stone accents. Marquise-cut diamonds typically have length-to-width ratios of 1.75 and 2.25. 



What could be more an ultimate symbol of love and romance than a heart-shaped diamond? Relatively rare, these are especially sought-after in pink diamonds. Depending on the grade, they can be quite expensive. Traditional heart-shaped diamonds have a length-to-width ratio between .90 and 1.10.


Named after British royal jeweller Joseph Asscher, the Asscher cut is almost identical to the emerald but whereas the emerald is rectangular, the Asscher cut is near square, with typical width to length ratios of between 1.0 and 1.05. This cut was once hard to find, but has become increasingly popular in recent years. Like the emerald cut, it is best reserved for high clarity gemstones.


A cushion-cut diamond is a square or rectangular shape with rounded corners and 58 facets. It is also known as a pillow cut. Cushion cuts look great with every type of setting, from antique styles to contemporary pave settings. The classic pillow shape tends to have ratios in the 1.10 to 1.20 range.

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Carat weight is one of the four fundamental attributes that determine the quality of the diamond. The other of the so-called "4 C's" are colour, cut and clarity. The word carat has nothing to do with the carat weight of gold, but is derived from the word carob seed, which was used in ancient times to balance weight. 

One carat equals 0.2 grams, but this really means nothing in terms of diamond size. A one carat diamond, for example, is not necessarily twice the size of a half-carat diamond, just as a 200-pound man is not necessarily twice as big as a 100-pound woman. It's important to also consider the distance in millimeters across the diamond's top, as well as the clarity of the diamond to determine its real size and appearance.

It should be noted that larger diamonds, those weighing 1.0 carats or more, are more rare, so you can expect to see the prices jump at that point as a result.

At Diamond Rocks, we can supply quality diamonds at all diamond carats. To help you to understand carat weight better, click here to see the dimensions of the popuar diamond shapes.

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Of the so-called "4-C's" that determine diamond quality, colour is probably the most readily apparent to the naked eye. The colour scale for grading diamonds is more about the absence of colour or, to be very specific, the absence of the colour yellow. The less visible colour, the more sparkle, the better quality and, thus, the more expensive the diamond.

Grades of Diamond Colour:


Very rare and hence will be more expensive. Generally, it is very hard to tell the difference between D, E or F grades to people other than diamond experts.

Near Colourless

Displaying only minute traces of colour visible only when compared to diamonds of higher quality.

Faint Yellow

Displaying only minute traces of colour visible only when compared to diamonds of higher quality.

Light Yellow

Yellow colour becomes increasingly apparent to the naked eye.



Of the so-called "4-C's" of diamond quality, clarity is one of the easiest to understand. Simply stated, it is a measurement of the number of flaws, called inclusions, in a diamond , which covers anything from scratches to blemishes to pockets of air or other non-diamond material inside the diamond. The fewer the inclusions, the rarer the diamond, and, therefore, the more expensive.

It should be noted that with most diamonds, inclusions are not usually visible without magnification. Thus, there is a wide range of acceptability and price. At Diamond Rocks, we follow the diamond clarity grading table below:



The diamond shows no inclusions of any sort under 10x magnification observed by an expert grader. These diamonds are extremely rare and very expensive.


Internally Flawless

The diamond has no inclusions when examined by an experienced grader under 10x magnification, but may have some surface blemishes.


Very Very Small Inclusion

Very, very slightly included. Under 10x magnification, imperfections are barely detectable even to expert graders.

VS1 - VS2

Very Small Inclusion

Inclusions are not visible to the naked eye, but 10x magnification may show minute crystals, clouds or feathers. These diamonds are less expensive than F - IF or VVS1 - VVS2 diamonds.

SI1 - SI2

Small Inclusion

Imperfections such as crystals, clouds, knots or feathers are visible under 10x magnification and may also be visible to the naked eye.

I1, I2, I3


Increasing level of imperfections that are obvious under magnification and perhaps even to the naked eye. These inclusions may affect brilliance and transparency. 

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The diamond's cut is another of the 4 C's of assessing diamond quality. The cut is not the same as the shape although the terms are used interchangeably; rather, the cut refers to the quality and precision of the jeweller's cut and how much light is reflected from the diamond. In essence, the cut is a measurement of the diamond's sparkle and many experts believe it is the truest measure of a diamond's beauty.

Shallow cuts are diamonds whose cut is wide at the top, which gemologists call the table, and shallow in depth, meaning that light escapes from the bottom. When this happens, the diamond can appear lifeless.

Ideal cuts are those diamonds whose cut is in perfect proportions, allowing most light to be reflected. This is the most desirable and most beautiful of all cuts.

Deep cuts are those that have a smaller table and a greater depth, allowing light to escape through the sides. What results is areas of darkness throughout the stone.

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Whenever you purchase a diamond, you should review its certificate, a professional report that is drawn up by a group of reputable gemologists. Diamonds sold through Diamond Rocks are graded by the GIA, the Gemological Institute of America, one of the most respected laboratories in the diamond industry.

Devised by a team of expert gemologists using microscopes, loupes and other industry tools, the GIA diamond certificate accompanies each and every diamond sold. It lists in great detail such information as diamond colour, clarity, cut, and carat weight, along with the diamond's measurements and other pertinent information.

The GIA certificate is useful not only in helping you to make a decision about which diamond to buy, it is also a record of value and authenticity and should be kept in your files for future reference.

To give you a full rounded assessment of your diamond, Diamond Rocks diamond jewellery will carry certificates from:

These organisations offer similar diamond information, ranking carat, clarity, colour and cut information. Please note, however, that some organisations may be more lenient than others when grading diamonds.

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Learn About Diamonds from GIA 

Learn About Diamonds from GIA


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