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The Diamond Glossary


When it comes to diamonds, it can feel like there is a lot to learn. But once you have a grasp of the key terms, choosing the right stone will feel a little easier.

Knowing about diamond definitions, grading and understanding the jargon can help when you are making that all important decision.

Here at Brown Family Jewellers we want you to find the right piece of jewellery or loose diamond, perfect for your style and taste - as well as your budget. Brush up on the diamond glossary we have put together below and feel a little more confident when making your choice:

The Brown Family Jewellers Diamond Glossary



This refers to a scratch or ‘bruise’ on a diamond.


When a diamond has been cut and polished it features characteristics that make up its anatomy. These include things like the table, pavilion and culet that make up a diamond and determine how it looks.



This is a diamond shape that enjoyed great popularity in the 1920s and is perfect for those who love vintage style jewellery. The square cut features a hall of mirrors effect, which means it sparkles beautifully in the light.




A rectangular shaped, step cut diamond. It is usually used in shoulder sets to complement a middle stone.



This is when a diamond’s girdle is subjected to too much force during the bruting stage and starts to show small cracks.


This is a type of setting for a diamond, usually featured in a ring. It enclosed the diamond completely and holds it in place.

Black diamonds

These are usually made in a laboratory but are essentially a diamond featuring lots and lots of inclusions and flaws, making it appear black. They’ve increased in popularity in recent years as people look for more alternative jewellery styles.


Used to describe any imperfections on a diamond’s surface.


This is the brightness of a diamond when light is reflected through. The more light is reflected, the more brilliant the stone.


When the rough diamond is shaped into its final polished state, this is known as bruting.




The weight of the diamond is referred to as the carat. 1 carat = 0.20 grams. The word carat with this spelling can also be used when referring to gold purity.


Every diamond comes with a certificate to prove its authenticity and confirm its grading. This is issued by the GIA.   


This term is used to describe how many inclusions and blemishes are in the stone and to determine its grading. Click here to read more about this.


This is the process used to separate a rough diamond into different pieces - using a diamond saw. These pieces are then made into separate diamond shapes.


Crown is the term used to describe the top section of a diamond.



Diamonds can be found in a range of colour grades, from the ideal colourless to less preferable ones which can appear yellow or even brown.

Diamonds are graded on their colour and when making your choice you can select from D gradings which are near colourless to Z where you can clearly see the colour. Many jewellers refuse to carry grades any lower than J, to ensure the diamonds available are good quality.


This is the facet at the tip of a diamond. It isn’t visible to the naked eye and is graded between ‘none’ and ‘small’.



A cushion shape is a square diamond with rounded edges that looks similar to a pillow, hence its name.


Not to be confused with the shape of a diamond, the cut is used to determine the diamond’s brilliance and light reflection and can be deep, shallow or ideal.

  • A deep cut means the light enters the diamond and reflects a small amount but mainly passes through the bottom, not offering a great deal of sparkle.

  • A shallow cut is when the light passes straight through the bottom.

  • An ideal cut means a good amount of light is reflected straight back up and creates lots of fire.





This is the height of the diamond and is measured from the culet to the table.


When looking at a diamond’s anatomy, this is the term used to describe the width of a diamond.

Diamond saw

This is a saw used to cut rough stones or for dividing and separating diamonds. A laser can also be used for this process.  




This is a diamond shape that is rectangular with diagonal cut corners. It was originally used to cut emerald stones and adapted for diamonds later.






This term refers to the flat, polished surface on a diamond that light enters through.  


Fancy diamond shapes are essentially any shape other than a round brilliant cut.


This is what an internal fracture in the stone is referred to as.


Fire is the coloured light that is reflected back through a diamond and what we usually think of when we consider how a diamond sparkles.


This is if any luminescence is emitted when a diamond is placed under something like a UV light, X-ray or white light.  

Four Cs

These are cut, clarity, colour and carat and are used by experts to determine a diamond’s quality and value.




The GIA (Gemological Institute of America) issues the certification and grading for diamonds. It developed the Four Cs system we use today and is considered to be the authoritative body for diamond grading.



When considering a diamond’s anatomy, the girdle refers to the edge, the joining section of the crown and the pavilion.



The measure applied to a diamond to recognise its quality.




Diamonds come in a wide variety of shapes and a heart is one of the most romantic styles you can choose.

HPHT enhanced diamonds

HPHT stands for High Pressure High Temperature and is the process used to change the colour and clarity of a diamond to make it a more preferable choice. It is placed in a machine that is heated to temperatures of up to 2,600°C to imitate the heat in the Earth’s crust.




Another word for naturally occurring flaws in a diamond. A good diamond has a small amount of inclusions, as it allows more light to reflect through it to create more sparkle. Inclusions show up as black, grey or white marks and contribute to the clarity grade a diamond is given.

Industrial diamond

Before diamonds are sold, they are inspected to see whether they would be best for use in jewellery or for industrial purposes. Industrial diamonds are used in machinery and tools to offer hard wearing equipment for cutting and precision work.

Irradiated diamonds

These are diamonds that have been artificially coloured by having their atomic structure changes by exposure to radiation.



Lab made diamonds

Diamonds can be made in a laboratory, offering a cheaper alternative to natural stones. They feature all the same physical and chemical properties of other diamonds but are made in a press machine that weighs hundreds of tons and operates at a very high temperature to convert carbon into a synthetic diamond.


This is the name for the small magnifying glass used by experts to examine diamonds. It can magnify 10x to help when grading diamonds when looking for inclusions.




With elegant pointed ends that elongate fingers, the marquise shape diamond has been enjoyed since the 1700s by French royalty and is a popular fancy diamond for many jewellery types.  


Moh’s Scale

This is used to determine how hard minerals are and is measured from 1 to 10. Diamonds sit at number 10 on the scale making them one of the hardest stones available.




One of the most popular diamond shapes for engagement rings, oval diamonds are elegant and simplistic with an elongated round shape and brilliant sparkle.




The pavilion is the bottom section of a diamond and extends from the culet to the girdle.



This stunning diamond shape elongates fingers and offers plenty of sparkle.


This is the final process of preparing a diamond for grading and involves someone called a crossworker polishing the diamond’s facets.

Polishing lines

These are small indentations that have been created during the polishing process, they must be removed during the final polish to ensure the diamond can be considered finished and ready.


This diamond shape is square cut and one of the most popular choices for engagement rings.





The term used to describe overall how the cut, colour, clarity affect the diamond and determine its gradings.




A term used when a diamond is not suitable for use and is of a poor quality.

Rough diamond

The stone in its original form is referred to as a rough diamond, before it is cut and polished.

Round Cut

A common diamond shape, the round cut offers some of the best scintillation in a diamond, making it a popular choice for many jewellery types.




Diamonds are polished on a cast iron wheel called a scaife (pronounced ‘skife’). These give diamonds their polished facets that light can then enter through.


Scintillation is the sparkle you see when moving a diamond and is seen as black and white flashes. To have great scintillation you also need a combination of good fire and brilliance in the stone. This is all determined by how it is cut.


Often confused with the cut of a diamond this is the outline the diamond appears as. Round, pear and oval are all examples of diamond shapes.


This is a single diamond, featured in a piece of jewellery for an elegant, simplistic look. Solitaire round diamond engagement rings are very popular, for example.




This is the largest facet of a diamond.



Wavy girdle

Referring to a diamond’s anatomy, this means the crown and pavilion facets are misaligned and so the girdle isn’t parallel with the table.


Some diamonds with colour gradings between D-H are considered colourless and can be referred to as white by some jewellers.

Now that you know some of the key terms, it’s time to brush up on the rest of your diamond knowledge via our in depth guides in our education section. Armed with this knowledge, you’ll be able to find a stunning piece of diamond jewellery in no time.

However, our team are also on hand to help should you have any queries about your purchase - just get in touch!