When buying the ideal diamond for yourself or that someone special, understanding exactly what you’re buying can be extremely confusing. Please check out my tips on buying the perfect sparkler! Here at BMG we believe you should have the information to understand what all those letters and numbers mean when choosing the perfect sparkly diamond. Diamond grading, and therefore pricing is all based around what is known as the 4 C’s This is expanded to – Cut, Colour, Clarity and Carat The price of the stone is determined by a mix of these points, for example: A half carat stone with a good cut, good colour, and poor clarity  will cost less than a half carat stone with good cut, good colour and excellent clarity. So understanding what you are buying is important to get the best stone for you. I'll explain a little more about the 4 C’s.


Determining the shape (cut) of the stone you want is a good starting point. The most obvious choice is a round stone. The reason for this is as follows: The round brilliant cut was mathematically formulated to get the most brilliance from the diamond. This means that nearly all the light entering the front of the stone is reflected back out of the top of the stone, giving exceptional “fire” or sparkle. Fancy Shapes (anything other than round) are desirable for the obvious reason that their shape is more exotic, and can often enhance the design of a particular piece of jewellery. Some of the available shapes (cuts of stones) are shown below: Diamond Shapes


Diamond colour is an important consideration when buying a diamond. The colour of the stone is graded on a scale of D-Z. The scale was devised in the 1950s by the GIA. The D was chosen as the start point as dealers where already using A, B and C. D, E and F diamonds are considered to be colourless and because of this are extremely rare and as such the price reflects this. Less than 1% of all diamonds are colourless. G, H, I and J diamonds are near colourless and as such represent a good standard to look for. The G and H are more sought after than I or J. K to Z diamonds show visible sign of yellowing or as it is sometimes called drawing colour. These stone aren’t worthless but it is widely agreed that they are not as beautiful as white diamond. However, once they reach a high yellow colour level they are considered a Fancy Colour and they gain a very high premium value.

 Diamond colour scale:

Diamond Colour Chart Yellow Fancy Diamond in one of our nose studs: Fancy Yellow Diamond Nose Stud


Diamond clarity refers to inclusions within the stone. These can be black, grey and white. Imperfections are graded under 10 x magnifications. The diamonds clarity has a big overall impact on the price of a stone, the fewer the inclusion the more desirable the stone. The scale runs as follows: IF - VVS1, VVS2 – VS1, VS2 – SI1, SI2 – I1, I2, I3 IF – Internally Flawless, very special and very rare, price reflects this. VVS – Very Very Slight inclusions. A good clean looking stone with very very slight inclusions that is difficult for a skilled grader to see under 10x magnification. VS – Very slight inclusions. Have minor inclusions that are difficult to easy for a skilled grader to see under 10x magnification. Typically inclusions in VS diamonds are invisible to the naked eye. SI – Slight Inclusions. Noticeable inclusions that is easy to very easy for a trained grader to see under 10x magnification. May or may not be visible to naked eye. NOTE: SI1 generally believed to be eye clean. I – Obvious Inclusions. Clearly visible under 10x magnification.

 Diamond Clarity Scale:

Diamond Clarity Guide


Carat is a measure of diamond weight, not size. A diamond can have poor cut to retain bulk (weight) equating to a higher selling price. One carat is split into 100 points. So a ½ carat diamond is also referred to as a 50 point diamond. Diamond Carat affects the price more than anything else. For example:  A diamond twice as heavy as another could cost up to four times more. This jump in price is due to the larger stones scarcity. Fancy Yellow & White Diamond Ring  made by BMG:Fancy Yellow Diamond Ring by BMGTIPS Here are some simple tips to aid you in the buying of a diamond:
  • Avoid popular diamond sizes (i.e: 25pt, 50pt, 75pt 100pt, 150pt etc.), often a diamond is cut leaving more rough diamond to achieve an easier sale at a popular size. Often looking for stone either side of these popular weights can get a good deal. Often the stone will have better cut which in turn leads to a better sparkle.
  • Carat and Clarity affect the price the most so getting the balance between then right means you will end up with the best stone for you. I.e: compromise slightly on clarity to get a slightly larger stone or vice versa.
  • Mounting - If the stone is to be mounted in yellow gold you may be able to compromise slightly on colour to gain on carat or clarity. If the stone is going into a white metal piece like platinum, you will want as white a stone as possible so may need to compromise slightly on carat or clarity.