Certified Diamonds

A Marquise cut diamond is designed to look visually bigger and is probably the best option if you want a big long look but for less money.

The Marquise diamond shape is probably the fourth most popular shape after the Brilliant Round, Princess Cut & Oval shapes of diamond.

Like the Brilliant Round diamond the Marquise also has 58 facets to make it as it is, done slightly differently to the brilliant round though.

The basic design is like an oval shape with the ends pointed, the Marquise shape came about when King Louis XV of France commissioned the diamond to be made to match the smile of the Marquise de Pompadour.

An aspect ratio of 2:1 is considered ideal for the classic Marquise shape.

When cutting a rough diamond, a Marquise cut can end up giving more carat weight compared to the Brilliant Round cut diamond.

The Marquise is a great design if you would like a ring that makes the finger look longer and slender.

The Princess Cut Diamond is the second most popular diamond shape and looks like a square from above.

After Brilliant Round Diamonds the Princess Cut shape is the next most popular shape of diamond. The Princess cut is popular for rings such as engagement rings and for anyone with long fingers is sometimes the best diamond shape to choose.

In a Princess Cut diamond a diamond colour of J may show some slight colour in the corners of the stone when it is unlikely to on a round diamond.

When it comes to the shape and dimensions of a Princess Cut Diamond you should pay attention to the Length to Width ratio. For a square you should look for a ratio of 1.0 to 1.05, if however you would like a slightly more rectangle shape you should look at a ratio of 1.1 and above.

The most popular shape of diamond is the Round Brilliant Diamond.

Accounting for 75% of all diamond sales the Brilliant Round diamond shape is the most popular diamond to buy and they are popular in engagement rings, stud earrings and pendants.

On a Round Brilliant diamond there are 58 facets and to get the Brilliance (the reflective qualities that make a diamond sparkle and shine) the diamond is cut to precise measurements to make sure that it offers the best brilliance. The Round Brilliant diamond offers the most Brilliance of all diamonds made.

Although the ideal proportions of a round brilliant diamond are known the cutters may not always get it absolutely to the precises proportions because of two reasons, firstly it can take up to 5 times as long to get the proportions absolutely perfect and perfectly symmetrical than it does to have a diamond cut to average proportions that are very close to the ideal cut proportions. Secondly the diamond cutter may be trying to keep the Carat (weight) of the diamond as high as possible which may mean the diamond won’t be cut to the ideal proportions (a diamonds Carat is a big factor in the selling price of a diamond).

The shape of the Diamond refers to the design and shape that the diamond is.

Originally diamonds were pretty much just done as Round diamonds, and today sales of round diamonds still commands 75% of all diamond sales.

However, there are other diamond shapes that can be bought if you want something a little different, not all work well in rings, some suit a chain or necklace better.

Below is a table of different shapes that diamonds can be made in to.

Round Brilliant	Princess	Marquise	Oval	Pear
Emerald	Radiant	Heart	Asscher

Some people (and even jewellers) mistakenly call the shape of  a diamond the “Cut” which is incorrect. You can read here about what a Diamonds Cut is.

You can read more about each different Diamond shape on the relevant pages from the links in the table above.

A Diamonds weight is measured in Carats, this is the measure of weight and not the size of a diamond.

As with the the other Four C’s, the Carat of a Diamond is measured on a scale too so that the correct weight can be found.

One Carat is measured as 100 points, so a diamond that is half a carat is 50 points, which would be written as 0.50 carats.

One Carat weighs 0.2 grams, so a 5 carat diamond weighs 1 gram.

As the size of the carat increases the diameter and also the depth of the diamond also increases. This is the reason why a 2 carat diamond doesn’t look twice the size of a 1 carat diamond.

As a guide half a carat of diamonds measures approximately 5.2mm in diameter and a 1 carat diamond is about 6.5mm in diameter. Below is a guide to the size of a diamond based on it’s carat size (sizing based on a round diamond).

The pricing of a diamond based on it’s carat size increases exponentially, as larger diamonds are rarer the price of these increases at a greater rate as the larger the diamond is.

When looking at the carat size of a diamond it is worth looking at buying one that is just underneath the next highest carat, for example buy a 0.9 carat as apposed to a 1 carat diamond. You will not be able to see any physical difference in size through the naked eye yet you may save hundreds or even thousands of pounds depending up on what carat size diamond you are looking to buy.

A Diamonds Carat is another part of The Four C’s that is important when buying a diamond.

The colour of a Diamond is a highly important aspect of a diamonds value with colourless diamonds fetching the most money.

The Diamond Colour grading scale is designed to rate a diamond’s colour as the less colour in a diamond there is the more valuable it is worth. The most expensive diamonds yet also the rarest are colourless diamonds.

Below is a Diamond Colour chart designed by the GIA.

Only around 1% of all diamonds are colourless (in the D,E,F range) and so there is very few of them meaning that the price of these diamonds is reflected by their rarity.

For the untrained eye a Diamond in the range from D to H it is very difficult to spot any colour despite the different grades demanding different prices. From around the grade I/J and below some yellowish colour can start to be seen.

The colour of a diamond is one of the main criteria of The Four C’s to buying diamonds.

The Cut of a diamond is another important aspect to the value of a diamond and is all to do with the proportions of the diamond and how it will reflect light.

The Cut of a Diamond when looked at for grading is actually to do with the proportions of the diamond, a symmetrical diamond will be bright and shine the light back out of it. Many people think the Cut is actually the shape of the diamond (Oval, Radiant, Emerald, Marquise, Pear, Heart) which isn’t, this is the shape and not the cut.

To rate the cut there are different different parts of the diamond that have to be studied, these are the Crown, the Girdle and the Pavilion.

Basically a brilliant or well-cut diamond with a high polish will make the light that passes through the diamond look amazing, making them sparkle, reflect and even split light up into the colours of rainbow in some cases! Cutting the diamond to the precise proportions will let light that comes into the diamond reflect right back out of the top of it, a diamond that is not well cut may have the light reflect out of the side of the diamond which won’t help it sparkle or shine.

When a diamond is cut too deep the light will reflect out of the side of the diamond. When a diamond is cut shallow then the light will go out through the bottom of the diamond as it won’t be able to be reflected.

Making sure that the diamond sparkles means that the cut has to be very precise and symmetrical to be able to offer the very best brilliance.

The Cut of a Diamond is one of The Four C’s that are looked at closely when a diamond is being certified.

The clarity of a diamond is an important factor of the quality of the diamond.

The Clarity makes up one of The Four C’s which is one of the important factors to look at when buying a diamond and assessing it’s value.

A diamonds clarity is assessed by looking for any tiny “inclusions” within a diamond, such things such as tiny cracks that may appear whitish or cloudy or inclusions of a foreign material within the diamond.

To check the clarity the diamond is looked at under 10x magnification to pick up any imperfections.

The Diamonds Clarity rating system is slightly different for different organisations.

The GIA (Gemological  Institute of America’s rating system is below and puts a diamond into one of 6 different categories and eleven grades. The higher up this scale the more valuable a diamond is (the scale below works from left to right for the best to worst).

The rarest and most expensive diamonds are Flawless diamonds, these contain no imperfections and have perfect clarity.

Other institutes who certificate diamonds use a very similar grading scale to that of the GIA, each individual organisations grading system will be added to the site.

When grading a diamonds clarity there are a number of factors that are looked at to determine the internal characteristics, including: Size, Number, Position, Nature and then Colour or Relief.
The most noticeable inclusions are what are assessed mainly to determine a diamonds grading which are referred to as characteristics.

Size
The first check of a diamonds clarity is the characteristics size. The larger characteristics are the lower down the clarity grading scale it will put the diamond.

Number
The number of characteristics a diamond has is the second factor that is assessed.

Position
The position of the characteristics is the third factor that is looked at. For example if it is directly in the middle of the diamond and close to the top under the table where it is more visible this will result in a lower grading than an inclusion that is near the girdle of a diamond where it becomes less easy to see.

Nature
The nature of any characteristics are the next factor to be looked at.
If it is an internal inclusion then the diamond will not be included in the Flawless or Internally Flawless categories, if it is on the external or just the surface then the diamond is only excluded from the Flawless category.

Colour or Relief
The fifth part of the clarity rating that is assessed is the colour and relief. The relief is looking for any characteristics that contrast with the rest if the diamond around it, the colour is then looked at with the more coloured inclusions being more visible.

When it comes to diamonds, before you buy you want to make sure you know about The Four C’s!

What The Four C’s represent are the main characteristics that are important in a diamond, namely:

• Colour
• Clarity
• Cut
• Carat

When a diamond is graded these 4 qualities in the diamond are the main ones that are looked for. Also, many also add a fifth “C” as Certificate.

The certification of diamonds can be done by independent companies which is recommended for anyone who is after buying a diamond.

For those who want true peace of mind when buying a diamond it is recommended that you buy a certified diamond that has been certified by an independent company & organisation.

A few examples of international companies who do diamond certification are:

• GIA (Gemological Institute of America)
• IGI (International Gemological Institute)
• IDL (International Diamond Laboratories)
• AGS (American Gem Society)
• EGL (European Gemological Laboratory)
• HRD (HRD Antwerp)

When buying a Diamond either in a shop or online you should check with the retailer if the diamond has a certificate and if so to check that the diamond certification was done by an independent organisation such as those listed above.

The above organisations do not buy, sell or give valuations of diamonds or other gems, they are there simply to give a certificate as to the quality of the diamonds they receive. That means that it is of no benefit in any way for them to wrongly classify a diamond as better than it actually is.