Handcrafted one of a kind diamond

Cut, Clarity, Colour, Carat

Understanding Diamonds


The various parts of a diamond and how well they are cut are included as part of a diamond’s cut grade. See below for an outline showing the anatomy of a diamond.


A diamond certificate is issued following an unbiased and professional examination to authenticate a diamond’s attributes. Without the correct laboratory certification it will be near impossible to rest assured that the other 4Cs are accurate.

There are many different diamond laboratories around the world but only one, Gemological Institute of America (GIA) has the reputation for being the worlds most accurate with relation to grading*. The GIA is a not-for-profit organisation, therefore has no financial interest in any of their certifications.

Laboratories such as IGI and HRD are generally one colour and clarity below GIA. Labs such as EGL are generally two to three colour and clarity below GIA standard. Australian Diamond Laboratories such as GSL, DCLA and IGL are equivalent to the GIA and at times know to be even stricter in colour and clarity grading.


Considered the second most important characteristic when selecting a diamond after cut. Acting as a prism, a diamond divides light into a spectrum of colours and reflects this light as colourful flashes. Therefore, the whiter a diamond is the more beautiful it will look.

Click here to view the GIA Colour informational video

When it comes to a diamonds colour, many people think all diamonds are brilliantly white – but this is seldom the case. Nature has provided a whole spectrum of colours in the makeup of a diamond, from flawless white (D – E) through to a yellow or brown (K – N).


A diamond’s cut grade is considered to be the most important characteristic. The cut of a diamond determines how light reflects within the diamond along with how brilliant and beautiful it will look. A diamond’s cut is crucial to the final beauty and value of the diamond.

Click here to view the GIA Cut informational video

Diamond cut grades are:

Excellent – Reflects nearly all light which enters the diamond. This cut only applies to Round Brilliant diamonds and maximises brilliance.

Very Good – Reflects most of the light which enters the diamond, often able to be purchased at a lower price than an Excellent cut.

Good – Reflects much of the light that enters the diamond.

Fair and Poor – Reflects only a small proportion of light that enters the diamond


The transparency of a diamond refers to how well the body of the diamond can be seen face up. The physical property of a diamond that allows light to pass through transparent diamonds appear clear, with an overall appearance of one colour, or any combination leading up to a brilliant spectrum of even colour. When light encounters a diamond, it can interact in many different ways. Light waves interact by a combination of reflection and refraction. Diamonds that do not allow or slightly inhibit the transmission of light are called opaque or gassy diamonds.

Currently there are no international diamond laboratories that report on the transparency of a diamond. To give you an example, a diamond with a transparency of Medium can sell up to 30% less than a diamond with Excellent transparency even though both diamonds have the identical size, colour and clarity. The transparency of a diamond will greatly attribute to the overall light performance of the diamond explaining why 70% of Excellent cut diamonds receive only a Medium Light Performance grading.

Carat Weight

Carat refers to the specific measure of a diamonds weight. One carat is equal to 100 points so a diamond of 75 points translates to 0.75 carats. This carat measurement is the most obvious factor in determining the value of a diamond. It is important to understand that two diamonds of equal carat weights can have significantly different prices depending on other quality grades.

A one-carat diamond (1.00ct) solitaire ring will always be more expensive than a diamond ring made up of smaller diamonds equalling one carat


Clarity is an indication of a diamonds purity. During the process of diamond formation tiny traces of crystal, carbon, gases or other elements can be trapped inside a diamond and these are called inclusions. These inclusions are defined by the GIA as “characteristics” which are inside a diamond or extend into it from the surface.

Click here to view the GIA Clarity informational video

Grades are:

FL, IF – Flawless, Internally Flawless: No internal or external imperfections. Internally Flawless: No internal imperfections.

VVS1, VVS2 – Very, Very Slightly Included: Very difficult to see imperfections under 10x magnification.

VS1, VS2 – Very Slightly Included: Imperfections are not typically visible to the unaided eye.

SI1, SI2 – Slightly Included: Imperfections are visible under 10x magnification.

I1, I2, I3 – Included: Imperfections are visible to the eye.

Conflict Free

Leonards Jewellers has a zero-tolerance policy toward conflict diamonds. The Kimberley Process, along with partnership with the United Nations, governments, and non-governmental organisations, monitors diamond exports to prevent the trade of illegal diamonds.

Leonards Jewellers only purchase diamonds through respected suppliers who also adhere to and enforce the standards. We also guarantee that all diamonds purchased from Leonards Jewellers are mined and processed in an environmentally and socially conscious manner and we source only from suppliers who uphold the same values.


Fluorescence refers to a diamond's tendency to emit a soft coloured glow when subjected to ultraviolet light. Approximately 33% of all diamonds have a fluorescence which can be seen under an ultraviolet light. The fluorescent properties of a diamond can cause a foggy or milky appearance to the naked eye which will result in a diamond which is diminished in both price and beauty. Leonards Jewellers carefully select certified diamonds that are 100% fluorescent free.

Light Performance

What makes one diamond more beautiful than another is the way it reflects and refracts light, better known as a diamond's light performance. Brilliance (white light), Fire (colour light) and Scintillation (sparkle) comprise the three categories of a diamond's light return. These three categories are graded from Low, Medium, and High to Very High. Excellent cut diamonds which achieve a High to Very High grade in all three categories are considered quite rare and normally sell for a premium.

Leonards Jewellers specialise in diamonds with High to Very High Light Performance certificates as certified by the GEMEX and OGI Systems. These companies are dedicated to delivering scientific and technological solutions that help consumers identify superior cut diamonds to make more educated decisions when buying a diamond.

View a short video on GEMEX Light Performance