| What is a Diamond? |
Diamonds are a colourless and extremely hard kind of pure carbon. They are formed at great depth - as much as 300km below the surface - under conditions of high temperatures and great pressures. Diamonds are found in diamond bearing rock called Kimberlite (sometimes also known as Blue Ground).
Diamonds are usually thought of as being clear, but they can also be coloured - yellow, blue, green, pink and orange. The colouring is created by elements that are mixed in with the carbon when the diamond is formed. A blue diamond, for example, contains tiny amounts of the element Boron. Naturally coloured diamonds are normally more expensive than colourless diamonds because they are much rarer. |
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| Cleaning and care |
Gold or platinum jewellery should be cleaned in warm soapy water (detergent is just as good). Brush it gently with an old toothbrush, particularly if there is debris caught behind the stone, which may happen if the ring is worn to do the washing up and similar. Avoid cleaning agents containing abrasives, including toothpaste.
Proprietary jewellery cleaner will clean your jewellery as well, but it will not necessarily work any better than warm soapy water. |
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| Cuts |
The cut of a diamond that gives it sparkle and the rainbow of colours. Light entering a symmetrically cut diamond bounces from facet to facet, prism to mirror, before coming out through the top of the diamond, full of brilliance and fire.
To achieve maximum effect the stone must be cut within a range of ideal proportions. If the measurements of the cuts are not correct the light will not be able to make best use of the internal reflecting surfaces and some of the best of the stone will be lost. It is the mark of a properly cut stone that they shine in the least light and are at their glorious best in sunlight. The main shapes of cut diamonds are: |
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The Round -
also called a ‘brilliant’ - is the most popular cut, largely because the 57 facets create a lot of shine and brilliance. |
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The Oval is a variation of the Round with 56 facets - technically called an ’oval modified brilliant’ - which give almost the same fire and scintillation. |
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The Emerald (or Octagonal) cut is usually rectangular. Unlike the Round it is a step-cut diamond with rows of between 48 and 50 facets that resemble as staircase. |
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The Princess is a brilliant-style diamond with sharp, uncut corners, normally in a perfect square. It generally has 76 facets, giving even more brilliance and fire than a Round. |
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The technical name for the Heart cut is the ’Heart-Shaped Modified Brilliant’ because it is a 59 facet variation on the configuration of the Round. |
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The Pear is an intermediary shape between the Round and the Marquise, cut in the shape of a water drop with the maximum glitter in the round part. |
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The Marquise (or Navette) has an elongated shape with a very luminous centre. The Marquise has 56 facets, like the Round, but is much more difficult to cut. |
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| Carats |
Diamonds are weighed in carats. A carat is 0.2 grams, and is divided into 100 points, so a 50 point diamond would be 0.5 carat. The term carat comes from the carob seeds that were originally used to measure the weight of diamonds. They were still being used to measure the weight of diamonds until the system was standardized at the start of the 20th century.
Large diamonds are, of course, much rarer than smaller stones, so the larger the gem the more expensive it is likely to be. 1 carat stone would, for example, be worth more than twice as much as a ½-carat stone of similar colour, clarity and cut. |
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1.25 CTS |
1 CT |
0.75 CT |
0.50 CT |
0.25 CT |
0.10 CT |
0.05 CT |
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| Clarity |
During the formation of a diamond minute internal features develop within the stone. These are called ‘inclusions’. They are normally minerals that are formed within and at the same time as the diamond, carbon that has not been changed to pure diamond or tiny fractures.
Although the number and type of inclusions can lower the value of a diamond, they have positive sides. Studying inclusions can help separate natural diamonds from fakes and, as no two stones have exactly the same inclusions, they can help identify individual gems. Completely flawless diamonds are rare and very valuable - the other end of the scale are stones with inclusions that are visible to the naked eye. The majority of gem diamonds used in jewellery fall between these two extremes.
In addition to these internal characteristics, diamonds can also have surface irregularities called blemishes which can include scratches and nicks. |
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| Colour |
People often think of diamonds as colourless, but in reality colourless diamonds are quite rare. The majority have very faint tints of yellow and brown.
Diamonds can have a wide range of other colours, including pink, red, blue, green and even black. The most intensely coloured diamonds are classified as ‘fancy diamonds’, and because the circumstances under which they were created are extremely unusual they are very rare and so attract very high prices.
Diamonds are normally graded by their lack of colour, so a stone with the highest colour grade has little or no visible colouration. The colour of diamonds is designated using the following grading scale:
- D. A totally colourless diamond. The highest grading possible: Rare and valuable.
- E. Colourless. Only an experienced gemmologist would be able to detect the minute hint of colour.
- F. Still a ‘colourless’ stone, but with a minor hint of colour, again only detectable by a trained grader. A high quality stone.
- G - H. Almost colourless, although a trace may be seen when compared with higher grades. Still a very high quality grading.
- I-J. Almost colourless, but a hint of colour may be discernible.
- K-M. Noticeable colour.
- N-Z. Very noticeable colour.
Each grade represents a spread or range of colour, not just one point along the series. In this range, a D colour diamond will always be the most valuable if all the other factors of clarity, carat and cut are equal. |
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