Established 1928

Rachel Flood is the fourth generation of the family working at Brooks Jewellers. In 2023, Rachel qualified as a "Diamond Grader" with GIA (The Gemological Institute of America). In addition, Rachel is currently studying for her full time "Graduate Gemologist" diploma with GIA so you can feel free to ask her about coloured gemstones too.

When you buy your diamond or gemstone jewellery from us we are equipped with the knowledge and expertise to help you choose the piece that best suits your  requirements.

Below is a general guide to diamonds. We recommend calling us on 051 421905 or dropping in-store with any specific questions you have. 

The 4 C's of Diamond Quality

The 4 C's are carat, colour, clarity and cut. The 4 C's apply to natural diamonds (mined from the earth) and lab-grown diamonds. 


Carat refers to the weight of the diamond. The size of the diamond is then a manifestation of it's carat weight. 

Carats (ct) are split into 100 points (pts). 1 Carat = 100 points.

So a 1.5ct diamond is 1 carat and 50 points.

Some trivia....... 1 carat is equal to 1/5 of a gram!


The diamond colour scale that is mostly used today was invented by the GIA in the early 1950's. This scale refers to colourless diamonds, sometimes called "white" diamonds.

The scale runs alphabetically from D - Z.

The scale starts at D, the absolutely best colour grade for diamonds as it doesn't show any hint of yellow, brown or grey.

As you go down the scale E,F,G,H etc., the more colour the diamond shows. D,E,F diamonds are considered colourless and diamonds in the G - J range are "near colourless".

Diamonds in the E - J range make up the majority of diamonds sold in jewellery today. Diamonds in this range don't show very obvious face-up colour and a diamond in the G - J range will be less expensive then a diamond in the D - F range, when all the other factors (carat, clarity & cut) are equal.

At the other end of the scale, diamonds in the S - Z range, would show some obvious yellow, brown or grey tints.


All diamonds, both natural and lab-grown, can contain clarity characteristics which are small "marks" or features in the diamond. They are usually referred to as inclusions.

The clarity grading scale is based on how visible these clarity characteristic are under 10 x magnification. That's why you often see diamond graders or jewellers use a 10 x magnification loupe (single eyeglass) to grade diamonds for clarity. 

 The scale starts at IF and goes down to I3.

  • Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification.
  • Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification.
  • Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification.
  • Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification.
  • Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification.
  • Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance.


The quality of a diamond's cut affects it's brightness, fire and scintillation - basically how well it sparkles and dances in the light. A diamond that has an excellent colour and clarity grade can be ruined by a poor cut.

When light enters a diamond, it bounces around inside the diamond before returning to our eye through the top of the diamond. This is what creates the "sparkle" that we see. A diamond must be cut within a range of specific angles in order for the light to bounce around properly inside the the stone and come out at the top again. If a stone is cut badly the light leaks out through the bottom (pavillion) of the diamond and therefore it won't sparkle well.

Cut grades for round brilliant cut diamonds range from Excellent to Poor.

 Cut (Shape)

The most popular diamond cut today is the Round Brilliant Cut. However, diamonds come in many other shapes such as oval, pear, princess cut square, cushion, emerald cut (rectangular) and the list goes on.

They are all beautiful and the best way to determine your preference is to see them and try them on in real life. 


We hope that this guide has been useful. Diamonds are a vast topic and sometimes the information overload can be overwhelming. 

Don't forget, that while knowledge about what you are buying is important, the most important thing is that you love your piece of jewellery and that wearing it brings you joy.

Please contact us on 051 421905 or call in-store with any diamond or gem related questions you have. Rachel, or one of the team, are happy to answer them in a clear, jargon-free manner.