As lovers of and professionals in grading diamonds we’ve devised a step by step guide on our 4 essentials to look at when picking out the right gem for you. These including Cut, Clarity, Colour and Carat, all important factors when considering the right diamond for you.

1. Cut

This refers to both the shape and proportion of the diamond, as well as its reflective qualities i.e. the finish and how much light is able to enter the gemstone. A large proportion of a diamond’s value is determined by the cut, so this is really important to look out for when choosing your diamond.


A diamond’s clarity, colour and carat weight cannot be altered, but it is a high quality cut of diamond that can release that extra special sparkle.

2. Colour


Diamonds are graded in colour from D to Z, the scale begins with D (colourless) and finishes at Z, a diamond of a light yellow or a brown colour. A colourless stone will allow the maximum amount of light to travel through increasing its brilliance and fire so therefore the whiter a diamond the higher its price.

The majority of diamonds used at Catherine Best are G or H in colour, these diamonds show virtually no colour to the naked eye, and do not attract the same higher premium as the official colourless range.

3. Clarity


This refers to the inclusions (internal) or blemishes (external) held by the stone. A diamond’s clarity is determined under a 10x loupe magnification with the highest grading called Flawless which has no internal or external flaws. Flawless and Internally Flawless diamonds are incredibly rare. We then enter the realms of VVS, VS, SI and I which all include variations of the word imperfect such as very very slightly imperfect, very slightly imperfect, slightly imperfect and imperfect.

It is important to remember that officially these clarity terms only become apparent under 10x loupe magnification and shouldn’t affect your experience looking at your diamond with the naked eye.

The high majority of the small brilliant cut diamonds we use in our jewellery are VS clarity and the larger diamonds we offer mainly stay in the bracket between VVS and SI. We can always procure any special one off diamond for you based on your own specific requirements.

4. Carat Weight

The carat weight of a diamond is simply how much it weighs. As with other factors, larger diamonds are more rare, therefore cost more, the carat weight is a fair unit of measurement to scale up the cost of a diamond. If you’re looking for a particular size of diamond the carat weight can be roughly guessed via the table below.

A final factor to consider is the fluorescence of a diamond, this is the effect that ultraviolet light (UV) has on a diamond. This is measured by the strength/intensity of visible light that a diamond exhibits when exposed to the UV light. Fluorescence does not compromise the integrity of the diamond, and the preference to buy a diamond that exhibits this is a personal one.  Other factors can affect the appearance of a diamond in a greater way than fluorescence like the way in which a diamond has been cut.

Due to the exceptional colour, clarity and cut which we at Catherine Best use in our diamond jewellery we usually opt for stones with little or no fluorescence as the 4 c's are always more important to us in the quality of a stone. However if this is something you would like, we can always procure gems as to customer requirements.
With over 25 years of experience in the jewellery industry here at Catherine Best we strive to source the best quality diamonds from reputable suppliers with whom we have forged strong and long standing relationships with.

We look for all these four factors when we are sourcing diamonds and will never cut corners to produce a product with a reduced price as quality is of the utmost importance to us.

Post By Laura Nugent