Diamonds 101

At Alberta Diamond Exchange, we believe in the importance of empowering our clients with the knowledge they need to make wise and informed decisions when purchasing a diamond.
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A diamond engagement ring is the quintessential symbol of love. Whether their style is classic or modern, the ring you propose with should be one that lasts a lifetime. At ADX, we’re here to guide you along as you make your decision.

Diamonds possess some key characteristics which set them apart from other precious gemstones. Becoming familiar with these characteristics will enable you to prioritize your needs and desires with confidence and make your decision with ease.

Anatomy of a Diamond

Before you begin your diamond search, you should know the parts of a diamond. The diagrams below demonstrate the anatomy of a cut and polished diamond. The proportions, angles and placement of each part play an important role in a diamond’s overall appearance and value.

Facet

“Facet” is the term used for a flat part of a cut and polished diamond. In a round brilliant diamond, there are 57 or 58 facets.

Diameter

The diameter is the width of a cut and polished diamond at it’s widest part. When looking at a diamond from the top, this is the distance from one side to the other.

Table

The table is the top horizontal facet of a diamond. The average table size is expressed as a percentage of a diamond’s average girdle diameter. The table is very important because it’s usually the largest facet, which helps light to enter and exit a diamond.

Depth

The depth of a diamond is measured from the table to the culet. The total depth is expressed as a percentage of a diamond’s depth when compared to it’s average girdle diameter. The depth is very important because it helps ensure light is refracted from one facet to another, and dispersed through the top of a diamond.

Girdle

The girdle is the widest part of a diamond that separates the crown from the pavilion. It is where a diamond is held when set in jewellery. The girdle thickness is described as a range from extremely thin to extremely thick. If the girdle is too thick, it can negatively affect a diamond’s sparkle while also adding unnecessary weight, increasing it’s price. If the girdle is too thin, a diamond may be more prone to chipping or breaking.

Crown

The crown is the upper portion of a diamond, from the table to the top edge of the girdle. It contains bezel, star, and upper girdle facets that gather and disperse light throughout the diamond.

Pavilion

The pavilion is the lower portion of a diamond, from the bottom edge of the girdle to the culet. It contains lower girdle and pavilion facets that reflect light back through the crown of a diamond.

Culet

The culet is the small facet at the bottom of a diamond intended to prevent damage to it’s point. The size of a diamond’s culet can affect it’s face-up appearance.

Source: Gemological Institute of America (GIA)

Carat weight

Diamonds have a standard unit of measurements: carats. Make sure you don’t confuse carat with karat (the purity of gold). The weight of a diamond is the most obvious factor in determining it’s value. As a diamond’s weight increases, so does it’s value. It’s important to know that the carat weight of a diamond does not always equal it’s size. For instance, a poorly cut 1.00 carat diamond may actually look like a 0.80 carat diamond!

Colour

Truly colourless diamonds are extremely rare. On the GIA colour scale, diamonds are graded on a range from “D” to “Z.” The value of a diamond decreases as the colour of that diamond increases. The closer a diamond is to a “D” colour, the more valuable it is.

The best way to determine which colour is most appealing to you is to view a selection of differently graded diamonds side by side. There is no “perfect colour” – it really depends on your personal preference.

Let’s talk about Fluorescence

Fluorescence

Diamond fluorescence, in its most simple form, is the effect that ultraviolet (UV) light has on a diamond. GIA grades the strength and intensity of a diamond’s reaction to long-wave UV rays, which is an essential component of daylight. While an increase in fluorescence can result in a lower price point, there may be negative effects on that diamond when exposed to natural lighting. A medium fluorescence diamond may appear cloudy or milky when exposed to daylight, where a strong fluorescence diamond may appear blue.

Source: Gemological Institute of America (GIA)

Clarity

The clarity of a diamond refers to the absence or existence of imperfections or clarity characteristics of that diamond. Because diamonds are formed under extreme conditions, they often contain imperfections that may or may not be seen with the naked eye. Internal imperfections are called inclusions, while those on the surface of a diamond are called blemishes.

Clarity is graded on a scale from “Flawless” (FL) to “Included” (I). Flawless diamonds are the rarest, and therefore the highest valued.

GIA Diamond
Grading Scale

Flawless (FL)

No inclusions or blemishes are visible to a skilled grader under 10x magnification.

Internally Flawless (IF)

Only blemishes are visible to a skilled grader under 10x magnification.

Very, Very Slightly Included (VVS1 and VVS2)

Inclusions are difficult for a skilled grader to see under 10x magnification.

Very Slightly Included (VS1 and VS2)

Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification.

Slightly Included (SI1 and SI2)

Inclusions are noticeable to a skilled grader under 10x magnification.

Included (I1, I2, I3)

Inclusions are obvious under 10x magnification and may affect transparency and brilliance of the diamond.

CUT

The cut of a diamond refers to the way light is reflected through each facet and angle. The higher a diamond’s cut, the more light returns to the eye, and the more appealing it’s appearance and quality. A diamond’s cut is graded on a scale from excellent to poor.

If a diamond is cut too shallow, the light escapes through the pavilion.

If a diamond is cut too deep, the light escapes through the opposite side of the pavilion.

If a diamond is cut to good proportions, the light is reflected from one facet to another and then dispersed through the top of the stone. This is what affects a diamond’s overall sparkle.

More on Cut

Polish

The polish of a diamond refers to the overall finish of that diamond after cutting it from a rough stone. Like a diamond’s cut, polish is graded on a scale from excellent to poor.

Symmetry

Also graded on a scale from excellent to poor, the symmetry of a diamond is based on how well the facets are aligned within the stone. A symmetrical diamond has even displays of brilliance, fire, and scintillation.

Shape

Not to be confused with cut, the shape of a diamond describes its actual shape. Here are the 10 most popular diamond shapes.

Depth and Table Percentages

The depth and table percentages of a diamond affect its proportions and cut grade. The tables below show the range of depth and table percentages for each cut grade and diamond shape.

Round Excellent Very Good Good Fair Poor
Table % 53 – 58 52 – 60 51 - 54 50 - 69 < 50 - > 69
Depth % 59 – 62.3 58 – 63.5 57.5 – 64.1 56.5 – 65 < 56.5 - > 65
Princess Excellent Very Good Good Fair Poor
Table % 67 – 72 59 – 75 56 – 82 53 - 85 < 53 - > 85
Depth % 64 - 75 58 – 80 56 – 84 < 56 - > 84
Oval Excellent Very Good Good Fair Poor
Table % 53 – 63 52 – 65 51 – 68 50 - 70 < 50 - > 70
Depth % 58 - 62 56 – 66 53 – 71 50 – 74 < 50 - > 74
Marquise Excellent Very Good Good Fair Poor
Table % 53 – 63 52 – 65 51 – 68 50 - 70 < 50 - > 70
Depth % 58 - 62 56 – 66 53 – 71 50 – 74 < 50 - > 74
Pear Excellent Very Good Good Fair Poor
Table % 53 – 63 52 – 65 51 – 68 50 - 70 < 50 - > 70
Depth % 58 - 62 56 – 66 53 – 71 50 – 74 < 50 - > 74
Cushion Excellent Very Good Good Fair Poor
Table % 61 – 67 58 – 70 56 – 71 54 - 73 < 54 - > 73
Depth % 61 – 67 58 – 70 56 – 71 54 - 73 < 54 - > 73
Emerald Excellent Very Good Good Fair Poor
Table % 61 – 69 57 – 72 54 – 74 51 – 79 < 51 - > 79
Depth % 61 – 67 57 – 72 54 – 74 54 – 79 < 54 - > 79
Asscher Excellent Very Good Good Fair Poor
Table % 61 – 69 57 – 72 54 – 74 51 – 79 < 51 - > 79
Depth % 61 – 69 57 – 72 54 – 74 54 – 79 < 54 - > 79
Radiant Excellent Very Good Good Fair Poor
Table % 61 – 69 57 – 72 54 – 74 51 – 79 < 51 - > 79
Depth % 61 – 69 57 – 72 54 – 74 54 – 79 < 54 - > 79
Heart Excellent Very Good Good Fair Poor
Table % 53 – 63 52 – 65 51 – 68 50 – 70 < 50 - > 70
Depth % 58 – 62 56 – 66 53 – 71 50 – 74 < 50 - > 74

Diamond Ratios

Any diamond shape other than a round brilliant is considered a “fancy shaped” diamond. When looking at fancy diamond shapes, the ratio of the diamond is very important as it affects the look and dimensions of the shape. Although it comes down to personal preferences, we’ve included some guidelines of ratios in fancy shaped diamonds.

Shape Preferred Too Long Too Short
Emerald 1.50 – 1.75 : 1 > 2.00 : 1 1.10 – 1.25 : 1
Heart 1.00 : 1 > 1.25 : 1 < 1.00 : 1
Triangle 1.00 : 1 > 1.25 : 1 < 1.00 : 1
Marquise 1.75 – 2.25 : 1 > 2.50 : 1 < 1.50 : 1
Oval 1.33 – 1.66: 1 > 1.75 : 1 1.10 – 1.25 : 1
Pear 1.50 – 1.75 : 1 > 2.00 : 1 < 1.50 : 1
Princess 1 : 1 > 1.50 : 1 < 0.75 : 1

Certification

A diamond certificate, or gemological laboratory grading report, is a document prepared by highly trained and impartial diamond professionals with advanced tools and technologies. It is a complete analysis of a stone and accurately documents specifics such as carat weight, cut, clarity and colour grades. It does not attach any monetary value to the diamond because the report is designed to be an accurate grading of that diamond, regardless of the market at any particular time.

ADX places its trust in the Gemological Institute of America (GIA), which is considered to be the worldwide authority for evaluating diamond quality. GIA created the 4 C’s diamond grading system, setting the standard for grading and identification practices used around the world.

At ADX, you can be assured that your diamond is ethically sourced and graded by exceptional international standards.