Everything you need to know about the GIA and the Argyle colour grading methods

The Argyle grading method has been one of the primary classification systems used to determine the quality of the Australian mine’s extraordinary fancy coloured diamonds. This grading method coexists with various third party grading laboratories’ methods to provide diamond sellers and buyers with a standardized means of assessing the value of the coloured diamonds originating from the Argyle mine. The results are recorded on a ‘gem identification document’, or a certificate of authenticity, and are an assurance of the characteristics of the identified gem for insurance and resale purposes. Other grading laboratories supplying identification certificates include the Gemmological Institute of America (GIA), the American Gem Society (AGS), the International Gemological Institute (IGI), the European Gemological Laboratory (EGL), the Gemological Science International (GSI), and Hoge Raad voor Diamant (HRD).

Not all specialise in fancy coloured diamonds so we will look at the two most internationally recognised systems that wholesalers and jewellers take into consideration when determining the price and value of the diamonds from the Argyle mine – the GIA and the Argyle.

The GIA grading method

The GIA grading method

Robert M. Shipley founded the GIA, or the Gemmological Institute of America, in 1931. He developed grading methods to professionalise the American jewellery industry. Shipley focused on utilising the 4Cs method; colour, cut, clarity and carat weight. These four criteria are the basis of the GIA grading method of categorising diamonds. Since then, the institute has been at the forefront providing training and accreditation for jewellers across the world so formal standards in gemology become standardised. Known for its stringent methods, the GIA quickly became the leader in the international diamond grading business. 

Why is there are need for the GIA?

The main reason for the establishment of the GIA is to allow for efficient communication in the market. Before the introduction of the GIA method, each diamond merchant had their own terminologies, grading methods and evaluation procedures. Without a standardised system, it was a quarrel of profiteering diamond peddlers and mistrustful end buyers. The GIA was the first attempt to unite worldwide jewellers into one system, which improved the diamond market for the better. 

How does the GIA colour grading system work?

A GIA qualified skilled grader determines each gemstone’s characteristic colour from the gem’s face up position in a specifically constructed environment and compares each against a master set of pre-graded gems in order to qualify the colour rating for the examined stone. In the case of diamonds, the GIA has two separate scaling systems for white, or colourless, and fancy coloured diamonds.

The GIA white diamond colour scale

White diamonds are scaled from D, where D represents a perfectly colourless diamond then as traces of yellow or brown colouring caused by the presence of nitrogen become more apparent, down the alphabet scale to Z.

The GIA coloured diamond colour scale

The GIA coloured diamond colour scale

As a global grading laboratory, the GIA examines gemstones from diamond mines all around the world so it developed a way to apply a consistent colour evaluation to every fancy coloured diamond that enters any of its labs. Recognising that coloured diamonds do not have a consistent experience of colour, three main attributes – hue, tone and saturation form what is essentially a 3D colour sphere to explain the GIA colour grading system.

Hue: the defining or characteristic colour of the stone.

Tone: how light or how dark a colour appears.

Saturation: how strong and intense, or how weak and dull the colour looks.

Its all in the name

From 2006, the GIA chooses a description from one of 27 hues for each fancy coloured diamond it examines. These are red (or pink), orangey red (or orangey pink), reddish orange (or pinkish orange), orange, yellowish orange, yellow orange, orange yellow, orangy yellow, yellow, greenish yellow, green yellow, yellow green, yellowish green, green, blueish green, blue green, green blue, greenish blue, blue, violetish blue, bluish violet, violet, purple, reddish purple (or pinkish purple), red purple (or pink purple), purple red (or purple pink) and purplish red (or purplish pink).

Note: at low levels of saturation and tone pink may be substituted for red as indicated in the list above. Similarly, brown/brownish or gray/grayish may be added to the descriptive colour name when darker, or lighter tones in warm colours such as red or orange seem to have a brown tint, or when the cooler hues of blue or green appear gray.

As neither light nor dark toned colours reach high saturation, the GIA devised a qualifier – a fancy grade – to describe the combined effect of these on the characteristic colour. This qualifier may be Faint, Very Light, Light, Fancy Light, Fancy, Fancy Dark, Fancy Intense, Fancy Vivid or Fancy Deep.

As an example of the naming convention for a GIA graded colour diamond is Fancy Light purplish pink.

A simpler but no less expressive system

The Argyle colour grading scale was created by company itself to grade the pink diamonds produced from their mine. The Argyle grading scale focuses on the level of colour in the stones, and the market evaluates the value and price based on this colouring. While the GIA method is still the preferred method for grading stones, the Argyle scale has become the staple when dealing directly with its pink diamonds.

The classifications of Argyle diamonds

The classifications of Argyle diamonds

The diamonds classified using the Argyle grading scale are distinguished by their colouring first and foremost. Out of all the coloured diamonds produced by the Argyle only three colours are highly sought after by investors and high end jewellers alike. These are colours are pink, red and blue. Within pinks there are additional grouping based on a modifying colour. These groups are:

  • Pink (P) – these stones display a prominent clearly pink colouring. The richest and most deeply saturated pink diamonds are called RED
  • Purple Pink (PP) – these stones look pink but a slight purplish tint prevents it from being an obvious pink. Those that have the darkest saturation of purplish pink tint are called Purplish Red (pRED)
  • Pink Rose (PR) – the pink hue of these stones is transformed by a hint of purplish brown
  • Pink Champagne (PC) – these pink tinted stones hold dominant traces of brown or yellow, giving them a distinctive champagne colour.

After a major colour group is assigned, the diamonds are further graded based on the strength, or saturation of the colour. For Pink, Purple Pink and Pink Rose an intense display of that colour is given a rating of 1, while the lightest has a rating of 9. Working in reverse the Pink Champagne class has 3 strength ratings, where 1 signifies the lowest or lightest presence of colour and 3 is given to diamonds with an intense display of pink champagne.

Comparing both colour grading methods

While both methods have their own merits and are widely used across the world, the GIA method is more widely accepted. The Gemological Institute of America aims to standardise the gem grading process, making it easier for investors to compare diamonds. The Argyle grading method is more specific to pink diamonds from the Argyle mine and should be used when classifying these beautiful stones. Essentially, when classifying any diamond, whether it be using the GIA or the Argyle method, you should always consult an expert in the field to ensure that you are getting the right classification for your precious stone. Contact Argyle Diamond Investments today and let us help you start your diamond investment portfolio.


  1. https://www.gia.edu/fancy-color-diamond-quality-factor
  2. https://beyond4cs.com/fancy-colored/how-are-fancy-colored-diamonds-graded/#:~:text=The%20GIA%20color%20grading%20system,more%20valuable%20the%20stone%20becomes.
  3. https://diamondscolored.co.za/uploads/7/3/4/0/73404465/coldiachartbklt__1_.pdf

Argyle Diamond Investments Pty Ltd are Australia’s largest supplier of Australian certified pink diamonds and have exclusive use of the Australian Pink Diamond Analytics program. This program is a data driven decision maker that tracks and statistically analyses the rarity, financial growth and value of all investment grade pink and blue diamonds. With this valuable information, Argyle Diamond Investments Pty Ltd can offer all clients an investment grade pink from $5,000AUD up. But, the highest growth diamonds, are the larger, stronger colour pinks starting from around $20,000AUD plus.


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