Diamond Chart

Your guide to universally recognised diamond standards.

2 CTS (200 pts)

1 CT (100 pts)

0.75 CT (75 pts)

0.50 CT (50 pts)

0.25 CT (25 pts)

0.18 CT (18 pts)

0.15 CT (15 pts)

0.10 CT (10 pts)

0.5 CT (5 pts)






Flawless and Internally Flawless










The Best Diamond School

The International Institute of Diamond Grading & Research prides itself on offering the diamond industry a fifth C: Confidence.

We only grade and inscribe diamonds that are 100% natural. Our specially developed industry leading proprietary instruments allow us to be confident that all diamonds we grade are natural and free of treatments as we spearhead the movement of bringing diamond grading into the 21st Century.

Our confidence extends further to the consistency and accuracy of our grading throughout all our global laboratories. We believe buyers should have confidence when purchasing a diamond and therefore we strive to offer a level of professionalism and integrity unrivalled in the industry.

All grading decision points involve the agreement of at least three separate graders and technology. The final most experienced grader then has access to all the results in order to assign the final grade to the diamond.

Every diamond in our labs is stripped of its identity and randomised. This ensures it cannot be attributable to a client and that each stage of the grading process the highest level of integrity is in place. This system of technology and security exemplifies the integrity, accuracy and consistency of the International Institute of Diamond Grading and ResearchThis system of technology and security exemplifies the integrity, accuracy and consistency.


Watch this video to understand more about the first C: Carat.


International School of Diamond

Diamonds range from colourless through to the whole spectrum. Almost all diamonds – 98-99% in parenthesis– have traces of nitrogen in their crystal structure. This causes the absorption of blue light, which imparts some degree of yellow tint on the diamond.

Colourless diamonds are those with insignificant amounts of nitrogen. These are graded at the top of the scale. Colour grades for these diamonds range from Colourless D through to Z and on to Fancy Vivid Yellow.

Natural diamonds can also occur in every shade of the rainbow. Known as Fancy Colours, these are graded according to their tone and saturation.


Watch this video to understand more about a diamond Clarity.


International School of Diamond

Science and art combine to make the most of a diamond through it’s cut. The right proportions, finish and polish create and increase internal reflections to maximise a diamond’s sparkle and enhance its impact.

The aim is to set off a diamond’s three key features: brilliance, fire and scintillation. Brilliance refers to brightness, or the return of white light due to internal and external reflections. Fire is the dispersion of white light into its component rainbow colours. Scintillation is a diamond’s distinctive sparkle, the sum of flashes of light both reflected and refracted as either the diamond or the light source moves.

With a clear understanding of the dimensions and angles of a diamond’s facets, the cutter combines individual skill with the optical properties of the diamond itself to bring it to life. When assessing the cut of a diamond, a grader will focus on the relative proportions of four key areas: the table (the top flat facet), the crown (upperside) the girdle (the edge around the diamond) and the pavilion (the underside). Our graders determine a diamond’s overall cut grade by taking into account its proportions, measurements, polish and symmetry.