Knowing Diamonds

The quality of diamonds vary so much. These natural gems are the hardest substance known to man and their allure has always been there. Prices are based on the four c's: namely colour, clarity, carat weight and cut. P. T. Miles will help our customers to select a diamond by showing you how to spot the differences in quality. Here is a brief but not exhaustive list of the things to consider.

Colour

Diamonds are often considered to be clear but this is not true, there being many different shades and colours. Most colours can be found in nature, from black, blue, green, yellow, orange etc through to clear. Lately, black diamonds have been in vogue although in the past these were considered to be of industrial quality. However the clear 'white' diamond still seems to be in most demand. Of these the colour grades are alphabetically arranged from D to Z, 'D' being the whitest and Z being very tinted to a yellowish or brown. Grades D to F are considered to be colourless, G to J are nearly colourless, K to M faintly tinted - usually yellow and N to Z with obvious colour to the naked eye.

The price you pay should reflect the quality of the diamond. Diamonds of exceptional colour are rare and very expensive if all the other 'C' characteristics are good. Colour ranges I to K are less expensive than D to H but are still a good colour, so on a limited budget they are well worth considering. Not all diamonds are officially graded by a gem testing laboratory but quality for quality are usually less expensive than the graded ones. For non certificated diamonds it is important to consult a professional but it should be remembered that diamonds should always be graded while they are loose from the setting. It is therefore unlikely that second-hand diamond jewellery will have a grading certificate. Colour of diamonds can be enhanced in the laboratory and all enhanced stones should be indicated by those selling the gems.

Clarity

When we talk about clarity we are considering so called imperfections that are naturally included within the diamond while it was being formed. Although the ideal clarity is one of perfection, this is rarely the case and if under 10 x magnification the stone appear perfectly clear, the price asked for this rarity is high. Most diamonds have some imperfection, referred to in the trade as inclusions. These are not really flaws unless the amount of these are too numerous which can affect the stone's durability. The highest grade viewed under a 10 x lens is LC (loop clean) or simply flawless. The next grade is VVS and VS (very very small and very small inclusions) Following this is SI, sometimes accompanied with a number - e.g. SI1 (Small inclusions grade 1) or SI2 (for grade 2). For the lower end are the grades P1, 2 or 3 (sometimes simply referred to as 1. 2 or 3 without the letter P). In a laboratory some stones are laser drilled and the inclusions disguised. Again as in the colour treatments, a jeweller should always advise a customer if this has been carried out.

Carat weight

Finally the weight of a diamond affects the price. A one carat stone is worth far more that two half carat stones. Why? It is simply because the larger stones are rarer to find and the smaller stones are often cut from larger ones and therefore there are more on the market. The weights are described as parts of 100. therefore 1/100th of a carat is referred to as a single point 25 points is a quarter carat, 50 points a half carat 75 points 3/4 of a carat and so on. Generally the larger the stone, quality for quality, the higher the price.

Cut

It is the art of the lapidary to cut the diamond to give it its maximum brilliance effect. A poor cut gives poor brilliance so the stone cutter has a great responsibility to ensure they get the best out of the stone. A Perfectly cut stone has good proportions. The popular round brilliant cut is still the most sought after although new cuts continue to be invented. If the stone is not properly proportioned, if it is too thick or shallow it will not show the brilliance that it should. As always you should take a look at a range of stones to appreciate the difference and be helped by your jeweller to see the subtle differences.