Diamonds – The 5 C’s

A combination of The 4C’s; Cut, Carat, Colour and Clarity determines a Diamond’s rarity and value.

The 5th C, Certificate gives you peace of mind, knowing that the Diamond you are buying has been independently assessed and graded.

Unless clearly labelled as ‘Lab Grown’, items found on our website and in our stores exclusively feature natural diamonds. Read our Lab Grown Diamond FAQs here.

1. Cut

In their natural state, diamonds are ‘rough’ and bear little resemblance to the sparkling gemstones we’re all familiar with. It takes a lot of time and skill to transform them into the beautiful diamonds that we set in our jewellery.

How well a diamond has been cut (Proportions, Polish and Symmetry) determines how well light can refract through the stone and in turn, how much it will sparkle.

Cut can also refer to the shape of the diamond.

The 5 Cs - Diamond Cuts

2. Colour

The less colour a white diamond has, the higher it is graded. The slightest hint of yellow or grey can make a dramatic difference to a diamond’s value.

Exceptions to this are Fancy Coloured Diamonds which can be Yellow, Pink or Blue and are prized for the intensity of their colour.

The 5 Cs - Diamond Colour

3. Clarity

Clarity refers to the number, size and position of any inclusions or blemishes within the diamond. These natural characteristics are, on the diamonds we select, very difficult to see with the naked eye.

Flawless diamonds are incredibly rare, which is reflected in their price.

The 5 Cs - Diamond Clarity

4. Carat

The Carat Weight determines the size of the Diamond. Because of their rarity, bigger diamonds would be more expensive than a smaller diamond of the same quality.

The 5 Cs - Diamond Carat

5. Certificate

The diamonds we use in our Engagement Rings have been independently graded and certificated by a recognised independent gemological institute.

We tend to use The Gemological Institute of America (GIA), International Gemological Institute (IGI) or Anchor (Birmingham Assay Office) who are renowned for their strict assessments.

The 5 Cs - Diamond Certificates


Phillip Stoner acquires diamonds through The Kimberley Process, an international certification scheme for rough diamonds, which guarantees that every stone we purchase is from a conflict-free zone.

The Kimberley Process is a joint government, industry and civil society initiative to stem the flow of conflict diamonds; ensuring that diamond purchases are not financing violence by rebel movements and their allies seeking to undermine legitimate governments. It has also helped stabilise fragile countries and supported their development.

The Kimberley Process is open to all countries that are willing and able to implement its requirements. Members account for approximately 99.8% of the global production of rough diamonds.