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Quality diamond jewellery is an investment. Like any investment, before you buy, it’s important you understand the fundamentals of pricing, quality, and options to make sure you are making an informed purchasing decision.

With this in mind, the diamond experts at Oh My Diamonds have put together an education centre to ensure you understand diamond basics, your purchase, and why smart buyers buy from Oh My Diamonds. Didn’t find the information you are looking for? Contact your Oh My Diamonds concierge Email to

Table of Contents:

  • i. Clarity
  • ii. Colour
  • iii. Cut
  • iv. Carat weight
  • i. Polish
  • ii. Symetry


Diamond clarity is a measure of how clear and flawless your diamond is. High clarity means light shines through perfectly with no blemishes or inclusions (birthmarks inside the diamond). Low clarity diamonds have visible imperfections that affect the transparency and brilliance of the diamond.
The main clarity characteristics are inclusions and blemishes. Inclusions are enclosed within a diamond, or may extend into the diamond from its surface. Blemishes are confined to the diamond’s surface. Clarity characteristics make every diamond unique. It’s extremely unlikely that two diamonds would have exactly the same clarity characteristics in identical locations.

  • Size
  • Number
  • Position
  • Nature
  • Relief

The effect of size is obvious: Large inclusions affect clarity more than small ones.
The number of inclusions is also important; a stone can have many tiny inclusions and still be high on clarity scale.
An inclusion’s position affects its visibility.

The nature of a diamond’s inclusion also influences its clarity grade. Large breaks or feathers have a greater impact on the clarity grade.
Relief means contrast or visibility. Dark inclusions are usually easier to see, and hence greater impact on clarity grade.

GIA Clarity Grades

  • Flawless
  • IF
  • VVS1
  • VVS2
  • VS1
  • VS2
  • SI1
  • SI12
  • I1
  • I2
  • I3

Clarity Definitions:


Flawless diamonds show no inclusions or blemishes of any kind under 10x magnification by a skilled grader.

Internally Flawless (IF)

An IF diamond shows only insignificant blemishes and no inclusions under 10x magnification by a skilled grader.

Very Very Slightly Included (VVS1 and VVS2)

VVS diamonds contain minute inclusions that range from extremely difficult to very difficult for a skilled grader to see under 10X magnification.

Very Slightly Included (VS1 and VS2)

VS stones contain minor inclusions that range from difficult to somewhat easy for a trained grader to see under 10X magnification.

Slightly Included (SI1 and SI2)

SI diamonds contain noticeable inclusions that are easy or very easy for a trained grader to find under 10X magnification.

Included (I1, I2 and I3)

Diamonds that fall into the I range contain inclusions that are obvious to a trained grader under 10X magnification.

The clarity you need depends on your budget and the type of jewellery you are buying. Looking for a ring with lots of small stones? You may be able to sacrifice on clarity a bit. Looking for a shining, brilliant solitaire? Then high clarity is a must!


Many people think all diamonds are colourless. This is not correct, and colour is an import part of classifying a diamond.
Diamonds that ranges from colourless to light yellow or light brown fall within the normal colour range (D-to-Z range in the colour grading scale).
Colour grades are,

  • D
  • E
  • F
  • G
  • H
  • I
  • J
  • K
  • L
  • M
  • N
  • O
  • P
  • Q
  • R
  • S
  • T
  • U
  • V
  • W
  • X
  • Y
  • Z

A diamond’s colour grade is based on how noticeable the colour is, also known as the depth of colour. The difference between one colour range and another can have an impact on price.

The levels or GIA Colour Scale can be divided into colourless, near colourless, faint yellow, very light yellow and light yellow ranges.

The D-E-F grades are considered colourless, diamonds in this colour range are extremely rare and valuable.

The G-H-I-J grades are near colourless. Diamonds with these grades look colourless face up and nearly colourless face down. The diamonds are popular because they combine fairly high colour with somewhat lower prices.

The K-L-M grades are faint yellow. Diamonds in this range show very faint yellow colour face-up and face-down.

N through R diamonds are very light yellow. They appear very light yellow face up and face down.

S through Z diamonds are light yellow. They show substantial colour face up or face down.

Once a diamond goes beyond the Z colour range, it moves into the fancy colour range; this includes Fancy Light, Fancy, Fancy Intense, Fancy Vivid, Fancy Dark & Fancy Deep depending on its hue, tone and saturation.

Master (reference) stones are used by laboratories in comparison to help determine a diamond’s depth of colour and its place in the D-to-Z range.


A diamond’s Cut Grade is derived from its Proportions, Polish & Symmetry. Cut is what make some diamonds sparkle or bling, and others lack the luster and brilliance of higher quality diamonds.
Proportions play the most important role in determining a diamond’s light performance (sparkle). Polish and Symmetry grades have a somewhat lesser effect.

The Cut Grade shows the diamond’s profile with its proportions in a table and percentage scale -- the profile includes crown angle, height percentage, girdle thickness, pavilion angle and depth percentage.
Cut is not shape! Round diamonds are most commonly used in jewellery, but other shapes such as pears, ovals, and even hearts are gaining in popularity. These diamonds are known as “fancy shapes.” Fancy shapes have their polish and symmetry grades recorded but without cut grade.

  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor

Carat Weight and Size

The weights of diamonds and most other gems are expressed in metric carats. One metric carat equals 0.200 grams (200 milligrams or 1/5 gram). A carat is divided into 100 equal units called points or cents. Diamond industry practice is to weigh diamonds to a thousandth of a carat, then round the weights to a hundredth of a carat.


Finish grading sets the maximum overall cut grade of a diamond. A good grade for either symmetry or polish limits a diamond to a maximum cut grade of Very Good; even if its proportions are Excellent. Finish is comprised of Polish and symmetry grades.


Polish is the condition of the diamond after polishing, plus any additional features such as nicks, abrasions, scratches or chips that may have occurred. Gemmologists and diamond graders look out for burn, polishing lines, rough girdle pits and surface graining to determine the polish element of a diamond’s finish.

  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor


Symmetry of a diamond refers only to the regularity of facet shape and the uniform arrangement of its 57 normal facets in a round brilliant cut diamond, princess and other standard fancy shapes. Severely asymmetrical diamonds may look odd or misshapen, whereas diamonds with excellent symmetry look great and uniform from any angle. A grader checks for twist, girdle variation, pointing, misshapen facets, roundness, extra facets, pavilion angles, crown angles and lower girdle facet to grade a diamond’s symmetry based upon number and location of faults at 10X visibility.

  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor


Some diamonds fluoresce, or glow due to fluorescence. Think of glow in the dark posters or how fabric lint looks on an otherwise clean black shirt when under a black light.

  • None
  • Faint
  • Medium
  • Strong
  • Very Strong


  • Gemological Institute of America (GIA),
    Established in 1931, GIA is the world’s foremost authority on diamonds, coloured stones, and pearls. A public benefit, non-profit institute, GIA is the leading source of knowledge, standards, and education in gems and jewellery.

    Through research, education, and unbiased gem grading and analysis, GIA strives to protect the gem and jewellery buying public by setting global quality standards.
  • International Gemological Institute (IGI),
    The IGI Diamond Report is essentially a statement attesting to the authenticity of a diamond and provides a reliable and accurate report of its identity and grade based on an internationally recognized system. Each diamond is scientifically analyzed by several gemologists who use their experience in combination with state-of-the-art equipment to produce an accurate description of the characteristics of the diamond and the quality of its cut. With its detailed information presented in understandable language, the different qualities of a diamond can be truly appreciated.
  • HRD Antwerp,
    HRD Antwerp's primary shareholder is the Antwerp World Diamond Centre (AWDC). The AWDC is a private foundation established in 1973 as the HogeRaadvoorDiamant (HRD) or Diamond High Council and represents the Belgian diamond industry.

    The HRD Antwerp diamond lab is the largest diamond lab in the world that issues reliable diamond grading and jewellery reports fully compliant with the rules for grading polished diamonds set by the International Diamond Council (IDC).