Diamonds – a buyer’s guide

A beginner’s guide to diamonds and what you need to know when buying them

There’s a lot more to diamonds than meets the eye. Setting out to choose one can be a daunting and confusing experience if you don’t know what to look for.

To help you along your way, we’ve put together this diamond guide so you can make an educated and stress-free decision when the time comes.

Diamond basics: the four C’s

Cut  Clarity  Colour  Carat

Getting value for money

Diamond basics: the four ‘C’s

Diamonds are grade by their “four Cs” – Cut, clarity, colour and carat (weight).

Here we explore what that all means so you can start to speak the language of diamonds. But first though, here’s some friendly advice –

Don’t get hung up on the technicalities

All four Cs are important in determining the value of a particular diamond and, as you’ll find out, prices can vary wildly depending on how a diamond is classed within each.

That said, it’s important not to get too hung on the technicalities, especially when it comes to how a diamond performs (rather than its size or weight).

In this case, looks are pretty much everything

What really matters is how the diamond looks to you.

Sometimes diamonds that don’t read so well can look great ‘in the flesh’. Conversely, diamonds that read well sometimes don’t live up to expectation.

Sure, get to know what you’re paying for, but let your eye be the final judge.

With that in mind, let’s get into it!


Diamond Cut

When it comes to diamonds, and coloured gemstones too , it’s the choice of cut that will enhance the value the most.

Most diamonds are cut with a view to retaining as much weight as possible from the original stone and minimising the visible flaws.

The cut also works to show off the stone’s brilliance to the best effect. There can be a big difference both in appearance and cost between an ‘excellent’ cut and an average one.

Also, some cuts are more popular than others and can attract a price premium. Round-cut diamonds are the most commonly sought, so more diamonds are cut this way. (This means it can sometimes be difficult to source a more unusual cut like a heart-shape.)

A common misconception

A lot of people believe that to really show off a diamond’s brilliance, it needs to be placed in a claw-style setting.

This simply isn’t true.

The main facets of the pavilion (bottom of the diamond) are crucial to the finished look of the diamond and the angle of the cut is set by the specific gravity (density) of the stone.

Light coming in through the crown (or top) of the diamond gathers in the crown facets and bounces off the back pavilion facets and light is returned to the eye. If the facets are not aligned, or there are unfortunately placed inclusions, there can be a loss of brilliance.

What all that means is it’s okay to set a diamond in a bezel (rub-over) setting where the sides of the stone are covered.

If the stone is properly cut, it will make no difference at all to the performance of the stone*.

Polish quality is important

The quality of the polish on facets is also important for the brightness of a diamond. Poorly polished facets will not allow enough light to go into the diamond or to reflect off facets. When polished and flat, they act like small mirrors, reflecting light back out to the eye.

*This is not the case with some coloured gemstone varieties. Many have different colours on more than one axis and need light from more than one angle to perform at their best.


Popular Diamond and Gemstone Cuts


Diamond Clarity

When classing diamonds, ‘clarity’ refers to the visibility of flaws and impurities or inclusions (rather than their presence or absence).

The simple fact is, all diamonds have inclusions, even those described as ‘flawless’. It’s all about how visible those inclusions are (or not).

Generally, (for colourless diamonds) the fewer and smaller the inclusions, the more valuable the diamond.

Along with colour, clarity is one of the major criteria used in classifying diamonds. Usually, the more ‘clear’ the diamond, the higher its value.

What this means is choosing a lower clarity diamond may enable you to buy a bigger stone for the same money (the exception is for high value pink, red and blue diamonds. Their rarity forgives their clarity).

Select diamonds based on how they look, not how they read

The tiny bubble-like inclusions in the central diamond are only visible under magnification

Depending on the location of the flaws there may be no difference in the appearance of two diamonds even though one has a lower clarity rating.

This is why it’s important to look at the diamonds you’re buying, not just read their specifications.

The best known gem grading system is from the Gemological Institute of America (GIA).

Most of the mined diamonds we offer at EJA have GIA certification. (Lab-created diamonds are not yet certified by the GIA) Diamonds are graded under 10x magnification using a small magnifier called a loupe, usually table down (point facing up).

In the GIA system, there are 11 grades (from the top):

GIA Clarity Codes


NOTE:  It’s very difficult for an untrained person to distinguish between a VS and an SI² diamond. It’s only when you get into the ‘I’ (or Piqué) grades that the imperfections start to become more visible.

Scandinavian Diamond Nomenclature

The Scandinavian diamond nomenclature (Scan. D.N.) and other systems vary slightly in their classifications. The most obvious is in the I 1 to I 3 range where clarity is often referred to as P 1, P 2 and P 3 (where ‘P’ stands for Piqué — pronounced pee-kay). This is relevant for diamonds graded by HRD (Antwerp).


  Diamond Colour

Photo of a cute-as-a-button bow ring features a heart-shaped Argyle pink diamond at its center with 'white' Argyle diamonds set into the bow.

This cute-as-a-button bow ring features a heart-shaped Argyle pink diamond at its center with ‘white’ Argyle diamonds set into the bow.

Diamonds are referred to as being ‘white’ (which actually means colourless or nearly so) and ’fancy’ coloured (which includes yellows, pinks, browns, blues, reds and greens).

‘White’ diamonds vary in colour from colourless (D – J) to pale- to light-yellow (K – Z), with colourless usually being the more expensive.

Fancy coloured diamonds have their own coding systems depending on the colour range.

For ‘white’ diamonds, a ‘lower’ colour (more yellow) diamond could cost more than an equivalent sized ‘higher’ (white) colour if the clarity and cut grading is higher.

For ‘white’ diamonds, generally less colour is better.

GIA Colour Classifications


NOTE:  G to J diamonds will not actually look very ‘yellow’. To an untrained eye, it is very difficult to see ‘shades of colourless’ — and sometimes, it’s not undesirable. For example, with vintage style rings, slightly tinted diamonds (particularly in old cuts) can enhance the design.


Diamond Weight (Carats)

Carat is the measure of weight of a diamond or gemstone. One standard metric carat is equal to 0.20 grams.

Within a type of diamond (or other gemstone), carat weight can also serve as an indication of physical size*. For example, a 1.00 carat diamond will be physically bigger than a 0.8 carat diamond of the same cut.

Points—what are they?

You’ll also often hear the term ‘point’. There are 100 ‘points’ in 1 carat. A 10 point diamond, for example, is equivalent to 0.10 carats (or one-tenth of a carat).

How big is ‘big’?

Many perceive there’s a lot of prestige attached to owning a 1.0 carat diamond ring (or bigger).

Round numbers like 1 carat and 2 carat sound impressive, but they can also mean big jumps in price for not much more diamond.

For example, a 0.95 carat diamond can be quite a bit lower in price than a 1.0 carat stone of the same quality, yet the actual difference in physical size is very small.

In many respects size is relative. A 1.0 carat diamond might look enormous on someone with very petite hands, yet not be very impressive on the finger of a person with large hands.

This is where ring design plays an important role in enhancing the perceived size of the stone or stones.

How big is a 1.0 carat diamond?

The following table will give you some idea of approximate physical size relative to weight.


*NOTE:  This rule doesn’t flow across different types of gem material. Different gemstone materials have different densities (specific gravity). Hence a 1.00-carat sapphire will be a different physical size to a 1.00-carat diamond of the same cut even though they weigh the same.


 Choosing the best value combination

We can’t stress enough how important it is to choose a diamond – especially a centrepiece stone—based on how it looks to you, not on how the certificate reads.

Quite simply there is little joy in owning a diamond that has all the credentials but doesn’t make you smile when you look at it. On that –

Buy the best, not necessarily the biggest

The basic rule of buy the best you can afford is no less true when it comes to diamonds.

Some people get very hung up on the idea that the diamond has to be a ‘big rock’, but we don’t support that.

Why settle for a dull, lifeless, poorly cut and high colour diamond when for the same money you could, for example, buy three smaller, much better quality stones that really dazzle. Or maybe go for a smaller stone but create a design that makes the stone appear bigger than it really is.

There are ways and means, and bigger definitely isn’t always better.

Having said that, ‘best’ does not necessarily mean a D Flawless diamond. This is often not a good use of your money. It may give you bragging rights in some circles, however, the visible difference between this and something like an E or F VVS1  to VS1 diamond will usually not be worth the price difference for a real world engagement ring.

Size (weight) contributes exponentially to cost

Within the same clarity and colour grades, ‘small’ diamonds cost less per carat than ‘large’ ones. But popular size points like half-carat and one carat also tend to spike prices.

By buying several small diamonds, you can either get more carats for your money, or get the same total weight for fewer dollars—especially if you can squeak in under the ‘magical’ half– and whole-carat numbers.

Buying smaller diamonds also encourages creativity. Some of our loveliest designs have arisen from a need to match a budget.

Let your eye be the final judge

With all that said, sometimes diamonds surprise us.

Their grading description can ‘read’ poorly and yet blow us away by their brilliance. It’s one of those cases where the whole can be greater than the sum of its parts.

It’s because of this that it’s crucial to speak to an expert who also has your best interests at heart – not just a salesperson who needs to make target for the day. Because of the way we run our business, we have built trusting relationships with our suppliers. This way we can be sure they will answer candidly when we are selecting diamonds for you.

Don’t overlook ‘alternatives’

Lab-created diamonds are becoming an increasingly popular option over mine-origin diamonds. You can read more about lab-created diamonds here.

Moissanite is also a popular alternative. Whilst it does occur naturally, most commercially available moissanite is lab-created, and is classed as a synthetic gemstone.

Its brightness and attractive pricing make it a viable alternative if you’re on a tighter budget. And some people just love them for themselves Read more about moissanite here.

Ready to start designing the perfect ring or other jewellery piece?

If you’re ready to get started, give us a call or drop us a line. We’d love to help you turn your ideas into reality.