What is a diamond?

• Mineral: Diamond

• Chemistry: C

• Colour: Colourless

• Mohs Scale of Hardness: 10

Diamonds are the hardest material on earth, 58 times harder than anything else in nature. Diamonds are typically 99.95 % carbon and the only gem made from a single element.

Diamonds form under high temperature and pressure conditions which only exist a specific depth (about 100 miles) beneath the earth's surface.

The Gemmological Institute of America (GIA)

‘Established in 1931, GIA is the world’s foremost authority on diamonds, coloured stones, and pearls. A public benefit, nonprofit institute, GIA is the leading source of knowledge, standards, and education in gems and jewellery’

Each diamond that is over a 0.30ct will come with its own GIA Grading Report this means that the stone has been independently graded by the GIA which gives our customers peace of mind.

Why aren't all diamonds graded?

Many jewellers will sell diamonds which are ‘self-certified’, unsurprisingly these are often wildly inaccurate and misleading to the customer. There are also a range of other grading labs which will grade diamond and gemstones but none are as accurate as the GIA. We want our customers to have complete confidence in us and their purchase which is why all of our diamonds that are over a 0.30ct are GIA graded.

The 4 Cs of Diamonds

A diamond's colour, clarity, cut and carat weight are collectively known as the ‘4Cs’. These are factors that, when combined, define a diamonds quality and ultimately determine its value.

Which C is the most important?

From experience we find that many of our customers select carat, colour and clarity based on their personal preferences. There is no right or wrong choice; it is dependent on the customer's individual inclination and specification that they believe will best suit their partner. The cut grade a is very significant to the beauty of the stone as it controls the brilliance, sparkle and fire of the diamond.

Off Report Factors

There are a number of factors that can impact the beauty of the diamond but will not appear on the stones GIA report, these are known as off report factors.

Here at Mill & Way we are dedicated to only providing the highest quality stones and our diamond buyer checks each stone for qualities that will not appear on the GIA report.


Fluorescence is the emission of visible light by a material when it is under ultraviolet (UV) rays. Fluorescence can vary in both intensity and colour, the terms used for describing the intensity of fluorescence are None, Faint, Medium, Strong and Very Strong.

Fluorescence can sometimes impact the beauty of the diamond, because of this we choose to only use diamonds in the Faint or None categories.

Some customers prefer the playfulness of a diamond with high fluorescence, please get in touch if you would prefer a stone that stands out in fluorescent lighting!

How can I be sure a diamond is conflict-free?

In 2002, a coalition of governments, non-governmental organizations and the diamond industry established the Kimberley Process to control the export and import of rough diamonds to eliminate the trade in conflict diamonds. Today 99% of diamonds in the marketplace are conflict-free.

For more information please follow the link below.



All of our designs have the environment in mind, by creating our products with Recycled Metal, Fair Trade Gold and Conflict Free, Ethical Gemstones.

Conflict-free refers to diamonds and gemstones which have not financed civil wars. Ethical diamonds go further, ensuring fair pay, safe working conditions, environmentally sound practices, and no human rights abuses.

Diamond Colour

What is diamond colour?

Diamonds come in a wide variety of colours, from colourless through near-colourless and even colours like blue or green.

The GIA colour grading system assesses the presence or absence of colour in the most commonly occurring colourless to light yellow. The yellow colour tint is a reflection of the trace levels of nitrogen within the diamond crystal structure.

Diamond colour scale:

GIA’s colour-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colourless, and continues with increasing presence of colour to the letter Z, or light yellow.

Diamond Colour Chart:

At Mill & Way we prefer to work with diamonds that are in the ‘Colourless’ and ‘near colourless’ range on the GIA diamond scale. We prefer to work with the highest colour range, but we do find that some customers prefer the slighter warmer colour tones.

D, E, F


G, H, I, J

Near Colourless 

K, L, M


N, O, P, Q, R

Very Light 

S, T, U, V, W, X, Y, Z


Why does the GIA colour grading system start at D?

Before GIA developed the D-Z Colour Grading Scale, a variety of other systems were loosely applied. These included letters of the alphabet (A, B and C, with multiple A’s for the best stones), Arabic (0, 1, 2, 3) and Roman (I, II, III) numerals, and descriptions such as “gem blue” or “blue white.”

The result of all these grading systems was inconsistency and inaccuracy. Because the creators of the GIA Colour Scale wanted to start fresh, without any association with earlier systems, they chose to start with the letter D—a letter grade normally not associated with top quality,

Does diamond colour matter?

Diamond colour is a completely personal preference. Some customers do prefer stones in the colourless range (D, E and F) as the higher colours are considered the most captivating. Whereas other customers prefer the charm of the warmer tones of the new near colourless range (G, H, I and J).

Fancy coloured diamonds

When does colour become a ‘fancy’ colour?

When a diamond falls outside of GIA’s D-to-Z colour scale, it is considered a coloured diamond (sometimes called a fancy-colour diamond). This includes all colours other than colourless to light yellow or brown.

On GIA Coloured Diamond Grading Reports, coloured diamonds are graded in order of increasing colour strength, from Faint, Very Light, Light, Fancy Light and Fancy to Fancy Intense, Fancy Vivid, Fancy Dark and Fancy Deep. Fancy Intense and Fancy Vivid generally command higher prices.

When does colour become a benefit?

Most diamonds used in jewellery range from colourless to light yellow and are graded on a scale from D (colourless) to Z (light yellow). Those with less colour, or closer to colourless, are generally more valuable.

Diamonds with deeper shades of yellow (more colour than Z) are graded differently and given a fancy-colour grade. For these coloured diamonds, a more vibrant colour typically means higher value.

Please contact us if you are looking for a yellow or fancy coloured diamond.

Black diamonds

The opaque colour of black diamonds is caused by dark inclusions. These can create an interesting and stylish alternative to the traditional engagement ring.

Please get in touch if you would like a black diamond in one of our rings!

What are Salt and Pepper diamonds?

Salt and pepper diamonds are stones with a high level of black and white inclusions resulting in a speckled greyish appearance. These give a modern twist to the traditional diamond.

Please get in touch if you would like a Salt and Pepper diamond in one of our designs!

Diamond Clarity

“Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).”

What is diamond Clarity?

Clarity refers to a diamond's relative freedom from clarity characteristics, which are classified as inclusions or blemishes. The clarity grade is a reflection of the purity and rarity of the stone.

Every diamond is unique, no stone is absolutely perfect under 10× magnification, though some come close. Known as Flawless diamonds, these are exceptionally rare and most jewellers have never even seen one.

At Mill & Way we specialise in eye-clean diamonds which means that we only sell stones that do not have clarity characteristics that are visible to the naked eye.

The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, colour or relief, and quantity of clarity characteristics visible under 10 times magnification.

Clarity is graded on a relative scale from Flawless to Included, based on the types of clarity characteristics present and their overall visibility at 10 times magnification.

Mill & Way will never use any diamond with noticeable imperfections to the unaided eye.


FL diamonds are Flawless


IF diamonds are Internally Flawless


VVS diamonds (1 and 2) are Very, Very Slightly Included


VS diamonds (1 and 2) are Very Slightly Included


SI diamonds (1 and 2) are Slightly Included

I1 I2 I3

I diamonds (1, 2 and 3) are Imperfect

Does diamond clarity matter?

Diamonds with lower clarity grades can look dull as the imperfections can stop the light from traveling through the stone reducing the refraction and light return.

Diamond Cut Grade

‘Cut quality is the factor that fuels a diamond’sfire, sparkle and brilliance. The allure and beauty of a particular diamonddepends more on cut quality than anything else.’ - GIA 

What is diamond cut?

The most important of the 4Cs, the cut grade refers to the overall cut quality and how the stones facets interact with light, creating what we see as the sparkle, brightness, and beauty of the diamond. This is determined by the stones' symmetry, proportion and polish.

The GIA grades the cut on a relative scale from Excellent to Poor.

it's important not to note that the cut is the quality of the cut not the ‘shape’ of the stone.

Why is Diamond cut important?

If cut poorly the diamond will appear smaller, duller and less sparkly. A well-cut diamond will reflect and refract light resulting in a beautiful, bright and sparkly diamond.

Here at Mill and Way we specialise in only the highest quality stones. We only sell diamonds with the best quality cut as we want our customers to have the most beautiful diamonds.

What impacts the quality of a diamond cut?

Cut is responsible for the quality and level of a diamond sparkle.

The cut is responsible for how light strikes the surface of a diamond, how much light enters the stone and how and in what form light returns to the eye.

The cut is based on the assessment of seven components:

Brightness - Also known as the ‘Brilliance’ this refers to the total light reflected from a diamond and how bright the diamond appears.

Fire - The Dispersion of light into the colours of the spectrum.

Scintillation - the pattern of light and dark areas and the flashes of light, or sparkle, when a diamond is moved.

Polish - The detailed and placements of the facets as well as the overall finish of the diamonds surface.

Symmetry - How precisely the various facets of a diamond align and intersect.

Weight ratio and durability - otherwise known as the precision of the cut, this is based on the craftsmanship of the diamond.

Diamond cut chart:

Many jewellers will sell a range of cut grades from including ‘poor’ cuts or will purposely choose not to inform their customer about the importance of the cut grade. Mill and Way refuses to compromise on quality by only selling excellent cut diamonds.

Diamond cut also refers to the shape and cutting style. There are many unique and wonderful diamond cuts but the most common is by far the round brilliant. Diamonds with shapes or cutting styles other than the round brilliant are known as fancy cut diamonds.


The brilliant cut is the most well-known facet arrangement, made of triangular and kite-shaped facets arranged to optimise the brilliance and light return.

Consisting of 57 to 58 facets the Round Brilliant diamond is the most popular shape for engagement rings. Oval, Pear, Cushion, Marquis and Heart-Shaped diamonds are also cut with a brilliant faceting style.


A Step-cut refers to a diamond with facets that run parallel to each other. The most popular step-cut design is the emerald cut.

Diamond Carat Weight

What is a diamond carat?

Carat indicates the total weight of a diamond, not the visual size.

Diamonds and gemstones are weighed in metric Carat, one modern metric carat equals 0.20 grams.

The Carat gets its name from the carob seed, these small seeds had a fairly uniformed weight that early gem traders would use as counterweights in their balance scales.

Mill & Way specialises in diamonds that are cut to emphasize beauty, not carat weight.

Diamond carat weight chart:

Carat weights can appear differently across different diamond shapes.

A diamond may have a higher carat weight without appearing larger; this is because the carat weight only refers to the total weight of the stone, not the visual size.

It's important to note that the carat weight does not represent size.

Is a higher carat weight better?

Carat weight alone does not determine a diamond's value.

Years of marketing campaigns have presented the carat weight as the most important of the 4 Cs, this misleads customers into believing that the larger the carat weight, the bigger the diamond will look when this is not always the case.

It's important to remember that the Carat weight is not the visual size of the diamond but just the total weight of the diamond on the scale.

Just like with people, you cannot estimate a person's height based on their weight alone. The carat weight only tells you the total weight of the diamond, not the stone's visual size.

Because there has been so much focus placed on the carat weight, many diamond cutters will cut the diamond in order to retain as much weight as possible to create a heavier stone that they can sell for a higher profit rather than create the most beautiful stone. The easiest area to retain weight on a diamond is on the pavilion or ‘belly’ of the stone.

A stone that has been cut in order to retain weight rather than create the most beautiful stone will result in a stone that weighs more i.e. a high carat weight but will look visually smaller from above. A stone that is cut with bad proportions will not only look smaller, but the proportions will not reflect the light in the correct way, resulting in a duller and less sparkly stone.

Gemstone Cuts

Types of engagement rings


Solitaire designs are rings that are set with a single diamond or gemstone. These are considered the most traditional and classic of the engagement ring styles.

Trilogy /3 stone designs

Each stone in a trilogy represents a couples past, present and future. This style can include a range of stone shapes and sizes.


This design gets its name from the ‘halo’ of diamonds around the outside of the centre stone. Traditionally the halo stones will be small round stones. The halo design can be traced back to the early Georgian era and we gained popularity throughout the Victorian era.

Shoulder set

This refers to designs which have smaller stones set into the band of the engagement ring. This style adds a touch of glamour to the traditional engagement ring.


Similar to the halo design, cluster designs have a number of stones that can vary in size and shape.

Toi et Moi - 2 Stone Ring

Meaning ‘you and me’ this style is known as one of the most romantic engagement ring designs, originating in France this ring represents the union between two souls.

Vintage designs

Vintage styles can come in a range of setting styles, these designs usually have intricate details around the setting and band. Please get in touch if you are looking for a vintage style ring.


950 Platinum

Perfect for engagement rings, this hardwearing and rare precious metal is a beautiful match for a diamond.

Consisting of 95% Platinum and 5% other metal alloys this dense silver toned metal is ideal for jewellery.

Platinum is also hypoallergenic which is perfect for those with sensitive skin

18k Yellow Gold

Radiating warmth and shine, yellow gold is the most traditional metal for engagement rings and wedding rings.

18k Rose Gold

With its glowing blush tones rose gold has gained popularity over the last few years and is now a very popular choice for engagement and wedding rings.

18k White Gold

Bright and glistening white gold offers an alternative to platinum. White gold is rhodium plated to give it a brilliant silver colour tone. .


Each of our rings are independently hallmarked at the Assay office which is run by the Goldsmiths company. These hallmarks are tiny stamps or marks within the band which represent the quality of the metal, the maker of the piece and the area and country the hallmark was stamped. These hallmarks guarantee to the customer that the metal has been independently graded for its quality and

For more information about hallmarking please follow the link below:







41 ½ 

D ½ 


2 ½  

42 ¾

E ½ 



F ½ 


3 ½  


G ½ 




H ½ 


4 ½  


I ½ 





J ½

5 1/2


K ½ 




L ½ 


6 1/2


M ½ 




N ½ 


7 1/2


O ½ 




P ½ 


8 1/2


Q ½ 




R ½ 


9 ½ 


S ½ 





T ½ 


10 ½ 


Q ½ 




R ½ 


11 ½ 


S ½ 




T ½ 


12 ½ 


U ½ 




V ½ 


13 ½ 


W ½ 


14 ½ 


X ½ 




Y ½ 


14 ½ 



Z + 1 

Z + 2 



Z + 3 

Z + 4

15 ½