Diamond Knowledge Centre

We understand that buying jewellery can be a daunting prospect, particularly if you are not familiar with some of the terminology; we have put together some information that you might find helpful in guiding you through the buying process:

What are the Four C’s?


Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. A carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, colour and cut.


Diamond colour is all about what you can see. Diamonds are valued by how closely they approach colourlessness, the less colour, the higher their value. (The exception to this is fancy-colour diamonds, such as pinks and blues, which lie outside this colour range.)

Most diamonds found in jewellery stores run from colourless to near-colourless, with slight hints of yellow or brown. GIA’s colour-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colourless, and continues with increasing presence of colour to the letter Z, or near-colourless. Each letter grade has a clearly defined range of colour appearance. Diamonds are colour-graded by comparing them to stones of known colour under controlled lighting and precise viewing conditions.

Many of these colour distinctions are so subtle as to be invisible to the untrained eye. But these slight differences make a very big difference in diamond quality and price.


Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).

Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value.

Internally Flawless (IF) – No inclusions and only blemishes are visible to a skilled grader using 10 x magnification

Very, Very Slightly Included (VVS1 and VVS2) – Inclusions are difficult for a skilled grader to see under 10 x magnification

Very Slightly Included (VS1 and VS2) – Inclusions are clearly visible under 10 x magnification but can be characterised as minor

Slightly Included (SI1 and SI2) – Inclusions are noticeable to a skilled grader using 10 x magnification

Included (I1, I2, and I3) – Inclusions are obvious under 10 x magnification and may affect transparency and brilliance


Cut is the factor that determines a diamond’s fire, sparkle and brilliance, and the allure of a particular diamond depends more on cut than anything else. Though extremely difficult to analyse or quantify, the cut of any diamond has three attributes: brilliance (the total light reflected from a diamond), fire (the dispersion of light into the colours of the spectrum), and scintillation (the flashes of light, or sparkle, when a diamond is moved).

An understanding of diamond cut begins with the shape of a diamond. The standard round brilliant is the shape used in most diamond jewellery. All others are known as fancy shapes. Traditional fancy shapes include the marquise, pear, oval and emerald cuts. Hearts, cushions, triangles and a variety of others are also gaining popularity in diamond jewellery. As a value factor, though, cut refers to a diamond’s proportions, symmetry and polish. For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, girdle and pavilion. A round brilliant cut diamond has 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion that’s known as the culet. The large, flat facet on the top is the table. The proportions of a diamond refer to the relationships between table size, crown angle and pavilion depth. A wide range of proportion combinations are possible, and these ultimately affect the stone’s interaction with light.

The distance from the bottom of the girdle to the culet is the pavilion depth. A pavilion depth that’s too shallow or too deep will allow light to escape through the sides or the bottom of the stone. A well-cut diamond will direct more light through the crown.

What is a certified or certificated diamond?

A diamond certificate is a report specific to an individual diamond, created by an independent gemmological laboratory. The diamond is fully evaluated, and the completed certificate records an analysis of the diamonds dimensions, clarity, colour, polish, symmetry, and other characteristics, along with a unique identifying reference code.

The Diamond Ring Company sells diamonds, rings, pendants, earrings and engagement rings which are all certified by independent diamond grading laboratories, either by EDR, EGL, GIA, HRD or IGI, which in our opinion are the most stringent, consistent, and reliable certificates currently available on the market.

Diamond Shapes

To most people, the word ‘diamond’ conjures images of the ever-popular and always classic round stone. Going this route is almost guaranteed to get you the reaction you’re looking for, but you can also choose one of the more unique shapes collectively referred to as ‘fancy cuts’.

Shape does not affect the quality of the stone. If it is well cut its brilliance and value will endure no matter what. The shape of the rough diamond crystal usually dictates the shape of the stone. All are cut for maximum fire and brilliance, but facet shape varies with the cut and as a result, filters light differently. Additionally, some designs are more suited to a particular shape.

Diamond Sizes

Diamonds are measured by carat weight, and not size. Two diamonds of the same carat weight could have different millimeter sizes because a diamond is three dimensional meaning length, width, and depth. The scale below is a comparison of sizes based upon carat weight with regular proportions.

What are ideal proportions?

The science behind diamond cutting is more or less an exercise in proportion. Changing the proportion of a diamond’s depth and width is done in order to maximize the stone’s brilliance. If the cut adheres to certain “ideal” proportions, the results can be spectacular. If poorly cut, the results can be so bad as to cause structural instability, which makes the stone susceptible to breaking. Because cut is so important, gemmologists have developed grading methods to assist consumers in determining a diamond’s cut. In general, they are: Ideal, Excellent, Very Good, Good and Fair.

What does ‘eye clean’ mean?

By definition diamonds with clarities of IF, VVS1, VVS2, VS1, VS2, SI1, SI2, are eye clean, i.e. clean to an unaided eye looking from top down from 25 cm distance.

What is fluorescence?

Fluorescence as a term means that a diamond will glow (in blue) under ultraviolet light. It was used originally in diamond certifications as additional information for identification. The impact of blue fluorescence on price depends on how noticeable it is. For some higher colour stones, fluorescence gives the stone a milky white appearance, which greatly lowers value. In some instances, the fluorescence is hardly noticeable and has minimal impact on the stone’s brilliance and value. Fluorescence often adds value to lower colour stones as it gives the stones a whiter, brighter appearance. Some buyers regularly pay better prices for highly fluorescent “I” colour and lower stones. Yellow fluorescence may require an additional discount. Generally, the higher the quality and price per carat the stronger fluorescence lowers value. For your information, we do not have any diamonds in stock that are milky or cloudy.

What are Clarity Enhanced or Treated Diamonds?

Diamond enhancements are specific treatments performed on natural diamonds (usually those already cut and polished), which are designed to improve the characteristics, and therefore the value, of the diamond in one or more ways. These include clarity treatments such as laser drilling to remove inclusions, application of sealants to fill cracks, colour treatments to improve a white diamond’s colour grade, and treatments to give fancy colour to a white or off-colour diamond.

What are Conflict or Blood diamonds?

Conflict diamonds are diamonds illegally traded to fund conflict in war-torn areas, particularly in central and western Africa. The United Nations (UN) defines conflict diamonds as “…diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognized governments, and are used to fund military action in opposition to those governments, or in contravention of the decisions of the Security Council.” These diamonds are sometimes referred to as “blood diamonds.”

Please note, The Diamond Ring Company does not sell conflict diamonds or clarity enhanced or treated diamonds.