The 4 C’s That Determine a Diamond’s Value

Diamonds are the most sought-after gemstone to adorn jewellery to show prestige and as a feature stone on the traditional engagement ring.

Diamonds were formed billions of years ago and are extremely rare because so few are able to survive the difficult journey from the pits of the earth to reach the earth’s surface. From the diamonds that are being mined today, only about 50 percent are thought to be high enough quality to be sold on the diamond market.

All the diamonds that pass through the Brown & Newirth workshop are certified and checked by our in-house GIA Qualified Diamond Grader to ensure they meet our high standards.

Their value and suitability to use in jewellery is determined by these four factors:

oval cut diamond


The go-to measurement for diamonds it the Carat weight, however, this is not the same as Carat size.

A marquise or oval diamond may be three times the length of a round brilliant diamond yet have the same Carat weight, therefore will be much more economical to purchase as an engagement stone for their size.


Cut refers to the diamond shape, proportions and polish.

Diamonds can come in many cuts with the most popular being round, oval, emerald, princess, cushion, trilogy, pear and marquise.

You can read more on our guide to diamond cuts here.


Diamond clarity refers to the absence of ‘inclusions’ or blemishes’ created when the diamond is compressed and formed.

When diamonds are graded they are given a clarity rating from flawless through to slight inclusion through to ‘pepper pot’ which are namely used in high street jewellery.

Anything rated ‘slight inclusion’ or above is clear to the human eye and the minimum standard for the diamonds we use in our jewellery.


This doesn’t refer to the literally coloured gems like yellow diamonds that include sulphates to give them a distinction shade.

Diamond colour refers to how white or colourless the diamond is.

Our diamonds are all grade G which is excellent for the industry considering the clearest diamond grade is a D and the scale goes right through to Z.

princess cut diamond

Our rings are handcrafted using G colour and SI clarity diamonds as standard. Ethically sourced, each is hand selected for it’s cut, polish and, symetry. Diamonds over 0.30ct are accompanied by a GIA grading certificate. Other diamond grades are available upon request.