The 4Cs, and the fifth one nobody talks about

Every diamond you will ever buy has been graded on four things: cut, colour, clarity, and carat weight. You have almost certainly read about them before. Most jewellers can recite them. The grades appear on every certificate, every price tag, every honest sales page on the internet.

We think there is a fifth, and it is the one that actually determines whether you will be happy with the stone you end up wearing.

## A quick refresher on the first four

**Cut** is the proportions of the stone - how the facets are angled, how light moves through it, how much of what enters the crown returns to your eye as brilliance. Cut is the only one of the four Cs that depends entirely on the cutter, not on nature.

**Colour** is a scale from D (colourless) to Z (noticeably tinted). Most stones sold for engagement rings are in the D–J range.

**Clarity** measures internal flaws - inclusions and blemishes, graded from Flawless down to I3. SI and VS grades mean the inclusions are too small to see without magnification.

**Carat** is simply weight. One carat is 0.2 grams. A two-carat stone weighs twice a one-carat stone, but because diamonds are three-dimensional, it looks larger by roughly a third across the face - not double.

## The fifth C: confidence

Confidence is knowing what you are buying. It is the difference between looking at a certificate and understanding what it tells you. It is knowing which grades matter for your ring and which do not. It is the reason a well-informed buyer ends up with a better stone, for less money, than one who simply asks for “the biggest and best.”

Confidence is also what a good jeweller owes you. Our job is not to sell you the highest-graded stone we have - it is to help you see why a particular stone is right for the ring you are commissioning.

## Certificates: GIA vs IGI

Two laboratories grade the vast majority of stones sold in the UK: the Gemological Institute of America (GIA) and the International Gemmological Institute (IGI). Both are reputable. GIA is generally regarded as slightly stricter on colour and clarity, particularly on larger natural stones. IGI is the dominant certifier for lab-grown diamonds and has become more prevalent for naturals in recent years too.

A certificate is not a valuation. It is a document describing the stone's measurements and grades. Price is set by the market.

## Where cut beats size

Take two stones at the same carat weight. One is a well-cut 1.00ct Excellent-grade round. The other is a poorly-proportioned 1.15ct stone of the same colour and clarity. The smaller stone will almost always look larger on the hand, because a well-cut diamond returns more light upward and appears brighter and more present. A badly-cut larger stone looks lazy - dark in the middle, dull at the edges. Cut is the grade we refuse to compromise on.

## Colour grades H through J

Below about colour grade J, a faint yellow tint becomes visible in daylight against white. Above it - H, I, J - the tint is invisible to anyone not comparing stones side by side against a white card. We have had clients sit across from two rings, one D and one H, and be unable to tell which is which until told.

If the ring is being set in yellow or rose gold, the metal itself warms the stone slightly, and the distinction between D and J becomes essentially invisible. Spending the difference on better cut is almost always the stronger call.

## Clarity: SI1 vs VS2 in practice

An SI1 stone has inclusions visible under 10x magnification. A VS2 stone has inclusions that are harder to find even at 10x. To the naked eye - which is the only eye that will ever look at your ring - the two are often identical. A clean SI1 can cost thirty per cent less than a VS2 of the same cut, colour, and weight.

## The quiet truth

The best diamond for you is almost never the highest-graded one we have. It is the one that looks brightest on your hand, sits best in the setting you have chosen, and falls comfortably within a budget you feel good about.

Come in and see stones in person. We will lay out three or four at your price point, across different grade combinations, and let your own eye decide. That is how almost every stone in our workshop has been chosen.