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email : info@jasonmcculloch.com.au

Diamonds


 

Diamond is the hardest natural mineral on Earth. It is made solely of carbon in crystalised form and is the simplest of all gemstones in composition, as well as one of the most spectacular.

 

Diamonds were created millions of years ago deep within the Earths crust. It is amazing to look at the beautiful gem on your finger and consider how ancient it truly is. It is the ideal symbol for eternal love.

 

Choosing a Diamond can seem daunting due to the huge amount of information available.

 

The quality and value of a diamond is determined by the Four C s and they can explain why some are rarer and therefore more valuable than others.

 

Below is an explanation of the Four C s; Cut, Colour, Clarity, Carat.

 

If you would like more in depth, technical information or have any questions at all please contact us for assistance (we have a qualified diamond grader on staff). Phone 02 49 571 610

 

When choosing a diamond trust your own eyes; you may think you’re no expert but remember if you think a diamond looks beautiful then it is and if you think it looks a little lifeless then it probably is dull. There are reasons that some diamonds “speak to our hearts” and have that life and fire and some don’t.

 

Read below to find out why some diamonds sparkle more than others.


CUT

 

 

Diamonds are cut in such a way to maximize the potential beauty of the stone. A good cut will enhance a diamonds beauty but a poor cut will considerably reduce it. Cut refers to the quality of workmanship not the shape of the diamond.

 

A Diamonds beauty is dependant on three factors; brilliance, dispersion (fire), and scintillation (or sparkle). These terms relate to the way light is refracted within the stone and reflected back through the top.

 

Cutting isn’t simply a matter of cleaving and sawing. Each diamond then needs polishing using other diamonds and powdered diamond abrasives. Polishing produces a number of facets on each diamond to create the sparkle with which we are familiar.

 

Round Brilliant Cut diamonds (RBC) have 58 facets. Many fancy shapes have a similar amount of facets and are cut to similar proportions. The proportions of a diamond must be mathematically accurate to maximize brilliance and dispersion. Sometimes you’ll hear this referred to as an “ideal cut”.

 

Brilliance is the white light reflected from the surface of the stone as well as the light that travels through the diamond and is reflected back up through the table and out the top. (The table is the large flat facet on the top of the stone).

 

Dispersion is the ability of the gem to break white light into its spectral colours. Dispersion occurs at the crown facets (around the table) and is also known as fire.

 

The importance of the cut cannot be understated. Two diamonds of the exact same size and colour and clarity grade can look completely different if one is well cut to proportion and the other is a poor cut.

 

It is the quality of the cut that gives a diamond its sparkle.


COLOUR

 

Most diamonds look colourless but there are many subtle shade differences and the closer a diamond is to having no colour the rarer and more valuable it is.

 

The internationally accepted GIA (Gemmological Institute of America) colour grading system uses the alphabet, starting at D through to Z.

 

Increasing yellow (or sometimes grey or brown) tone decreases the value of a diamond (as they are more common than colourless gems) until the yellow colour becomes so intense that they are classed as “fancy” yellow which are quite rare. Other fancy colours are pink, violet, blue, green, champagne and cognac. The colours are caused by traces of other minerals within the diamond, for example the yellow colour is caused by nitrogen.

 

To decide the colour grade of a diamond, the grader must determine the amount by which the colour deviates from truly colourless. As very few diamonds are truly colourless, the grader has to be able to measure the amount of colour (yellow, brown, grey etc) that is present in the stone.

 

The subtleties of colour are such that comparisons must be made to stones of a known colour. This is accomplished by the use of a set of master stones that have been specifically graded by a recognized trade laboratory for colour comparisons only.

 

Diamonds are always graded for colour whilst unset. Once set into jewellery the colour can only be estimated because the stone cannot be viewed in full and will reflect some colour from the surrounding metal.


CLARITY
 


Diamonds are a natural crystal and because of this they contain tiny internal marks called inclusions (external marks are called blemishes).

 

 Inclusions can be present in the form of mineral specimens, fractures, cleavages, clouds and external marks. All diamonds have inclusions of some type and if sufficient magnification is used they can be seen. Most inclusions are not visible to the naked eye.

 

Inclusions do not necessarily weaken a stone and when they do not interfere with the passage of light, they do not affect its beauty. Inclusions can be considered a diamonds’ birthmarks and as such can be used to identify particular stones as no two diamonds have the same inclusions.

 

When diamonds are graded for clarity the worldwide standard of 10 times magnification is used, whether by using a loupe (eyeglass) or a microscope. The fewer, and smaller the inclusions, the rarer and more valuable the diamond.

 

The internationally accepted clarity grading system we use in Australia is the GIA (Gemmological Institute of America). In this scale any stone graded as an SI (slightly included or small inclusions) or higher, has no inclusions that can be seen with the naked eye.


CARAT

 

 

Before the days of standardized weights, it was necessary for merchants to rely on the use of objects which were fairly common for weight assessment. Different types of dried seeds were used for small weights, including the dried seed of the carob, which was called a carat. It was used because their weight was extremely consistent from seed to seed.

 

The weight of a metric carat was standardized in the early 20th century and is 0.2 grams or one fifth of a gram. The abbreviation for carat is ct.

 

The carat is divided into one hundred points (just like cents in the dollar). Weights that are not whole units are expressed as decimals, for example 1.25ct, 1.37ct, 5.48ct and so on. When stones are below one carat, a zero should be placed in front of the decimal point, for example 0.65ct, 0.23ct, 0.98ct etc.

 

Where polished diamonds are much smaller than one carat they may be referred to as so many per carat (p.c.) such as 100 p.c. (meaning 0.01ct each) or 50 p.c. (meaning 0.02ct each) and so on. As the divisions in a carat are called points it is acceptable to describe a diamond as being so many points. For example a 50 point diamond is 0.50ct or half a carat.

 

Loose diamonds can be weighed on a diamond balance (special scales for measuring extremely small weights accurately), however mounted stones cannot. Mounted or set stones must be measured and the carat weight is then determined using a specific mathematical formula.

 

The value of a diamond varies dramatically with weight because the larger the stone the rarer it is. Therefore five diamonds of 0.20ct each (total one carat) are not as rare and valuable as two diamonds of 0.50ct each (total one carat). To give some perspective, of the millions of diamonds that are cut and polished into gems only 2% are larger than 0.20ct or one fifth of a carat.

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Diamonds are Forever


This beautiful and timeless pendant is set with a large Round Brilliant cut Black Diamond and small Round Brilliant cut white diamonds. It is worn on a strand of exquisite Baroque pearls.

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This classic and stylish modern design features a stunning one carat Round Brilliant cut diamond mounted in a 2 tone 18ct gold double bezel setting.

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See some of our Jewellery come to life from design stage through manufacture to finished piece Click here
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