John Pass

At John Pass, we have experienced and knowledgeable staff to help you choose the perfect Diamond.

We explain Diamonds to you using the 4C’s which are criteria used to grade Diamonds and help you to choose the perfect Diamond.

The 4 C’s are:
• Cut
• Clarity
• Color
• Carat weight

Cut

Everyone wants their Diamond to sparkle, and the way it is cut affects this. It is important that as much light as possible which goes into the stone is reflected back to your eye, and the way the stone is cut affects this.

Cut refers to the way the facets on the stone are arranged in relation to each other and the angles they are all at. If the stone is cut to Ideal Proportions, most of the light which goes in will reflect back to your eye and this is what we are looking for in a good cut.

Light enters through the top of the stone, called the table and travels to the back of the stone called the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to your eye.

The sparkle of the stone is known as its Brilliance and the flashes of colour within the stone are known as its fire.

These pictures show how in the Ideal Cut light reflects back to the eye whereas in a stone which is cut too deep or too shallow, it goes out through the back of the stone.

Clarity

When diamonds were formed in the ground many millions of years ago, the great heat and pressure which creates their hardness and brilliance also left some inner flaws which are called inclusions. The visibility, number and size of these inclusions determine what is called the clarity of a diamond. Diamonds with less inclusions have more brilliance and are more sought after and therefore have higher value.

We use the GIA (Gemmological Institute of America) grading system to describe the level of inclusions within the stone.

Diamonds are graded for clarity using 10x loupe magnification (jewellers eyeglass).

The GIA scale goes from flawless to included:

Grade (GIA)	What it looks like to you
F (Flawless)	No inclusions inside or on the surface of the stone. Very Rare.
IF (Internally Flawless)	No inclusions inside the stone but some minor surface inclusions only seen with magnification. Rare.
VVS1-VVS2	Very, Very Small Inclusions. A gemmologist would find it hard to see inclusions within these stones using 10X magnification.
VS1-VS2	Very Small Inclusions only seen with difficulty using 10x magnification.
SI1-SI2	Small Inclusions seen using 10x magnification
I1-I2-I3	Inclusions which can be seen to the naked eye

The pictures above give an idea of how easily you inclusions vary between grades.

Colour

This means how white the Diamond is. The rarest and most valuable Diamonds have no trace of colour in or have a definite colour such as Blue or Red and are known as Fancies. The GIA Scale of Grading uses letters to show whether a stone is White or has a hint of colour. The European System, CIBJO, uses words to describe the colour. This, of course, is reflected in the price.

International Colour Grading Systems
CIBJO		GIA
Exceptional White	+	D	Colourless
		E
Rare White	+	F
		G	Near Colourless
White		H
Slightly Tinted White		I
		J
Tinted White		K	Faint Yellow
		L
Tinted Colour		M
		N	Very Light Yellow
		O
		P
		Q
		R
		S-Z	Light Yellow

Carat Weight

A carat is the unit of weight by which a diamond is measured.1 Carat =0.2 grammes Because large diamonds are found less often than small diamonds, Diamonds with larger carat weights increase greatly in price.

The pictures above show how Carat weight varies in Round Brilliant Cut Diamonds.

Shapes of Diamonds

These are just a selection of the shapes of Diamonds we sell. We are happy to try to find your desired shape for you.

Diamond Certificates

Diamond Graders assess each stone to decide its grading so it can be priced and sold. If they were to grade every Diamond in detail, many small stones would become unrealistically priced as a Certificate goes into great detail about the stone. Some of our Diamonds come with a Free Valuation which will give and approximate grading for the stone within a range – for example, colour F to G. This is because we have not paid for the stone to be certificated to keep the price realistic. Many of our larger and higher graded stones, particularly in the Mastercut and Candour ranges, come with a GIA Certificate explaining and guaranteeing the quality of your stone in great detail. We are happy to get any of our Diamonds certificated (there may be a charge for this) or to get you a loose stone which comes with a certificate and set it into a mount of your choice.