When buying a diamond there are a choice of certifications. All diamonds listed on our website are certified by the top laboratories. These include the following:
The GIA invented the famous 4cs outlined previously i.e. Cut, Colour, Clarity and Carat. They also devised the colour grading scale of D to Z and clarity scale of Flawless to I3, which are recognised worldwide throughout the jewellery trade. In addition they are credited with creating the first diamond loupe (magnifying device).
GIA Diamond Certification – Origins:
- Between two and five professionally trained gemologists examine each diamond before preparing the grading report.
- Each stone is weighed and measured and the stone’s culet (the flat face on the bottom of a gemstone) and girdle (the thin perimeter of a diamond, dividing the crown above from the pavilion below) thickness are described.
- Colour is determined by comparing the diamond to a set of master stones of predetermined hue.
- Clarity is assessed under microscopic analysis using a 10x magnification loupe. The characteristics are then marked on a diagram or a picture of the stone.
- Polish and symmetry grades are decided according to the inspection criteria of diamond craftsmanship. In the case of a round stone an overall grade to describe the Cut is also determined by specific criteria. Besides those previously mentioned, another three criteria are used to describe the appearance of each brilliant round-cut diamond. These are brightness, scintillation, and fire.
- Finally, after all these processes, a set of highly skilled and experienced gemologists independently check the stones. Once an overall agreement is made the final report can be completed.
GIA Gem Laboratory, 580 Fifth Avenue, Suite 200, New York, New York 10036
This is the main employer of the Antwerp diamond sector, established in 1973 as the ‘Hoge Raad voor Diamant’ or the ‘Diamond High Council’. It represents the Belgian diamond industry, both at home and abroad. Besides producing diamond certificates, it also provides research for the diamond sector and helps create innovative technologies to support the diamond sector. The HRD is certificate is very respected throughout the industry.
HRD Diamond Certification – Methodology:
HRD certificates comply with international standards. Like the GIA, diamonds are graded independently by a few specialist gemologists. Here too, stones are submitted anonymously to the graders without revealing the identities of the owners. As with the GIA, senior graders randomly double-check the consistency of the grading. In general the larger or more expensive the stone, the more gemologists grade it. Grades are submitted anonymously and independently and results are agreed based on average results.
The International Gemological Institute’s world headquarters were founded, and to this day are still based, in Antwerp. It has offices worldwide, including New York, Hong Kong, Mumbai, Bangkok, Tokyo, Dubai, Toronto, Los Angeles, Tel Aviv and Cavalese. It is the largest independent gem certification and appraisal institute, set up in 1975 and is one of the leading gemological institutions worldwide. It is also renowned for quality and is highly respected. Starting out in one room, today the organisation comprises 450 professionals and they produce 1 million reports a year. In 1982 the IGI set up the world’s first courses in polished and rough diamonds.
Each diamond graded by the IGI is scientifically analysed by several expert gemologists. These experts team their knowledge and experience with state-of-the-art equipment to prepare an accurate description of each diamond. All gemologists must agree on each diamond before a grading report can be issued.
- Weight is determined using an electronic balance that measures to ten-thousandth of a carat.
- Measurements are taken, and every angle and facet is measured to evaluate polish and symmetry.
- Clarity is graded by determining the number, nature, size, and position of any internal characteristics. This analysis is performed by means of a high-powered microscope and a 10x magnification loupe.
- Again, colour is described by comparing the diamond to a set of master stones of predetermined hue.
IGI World head office, Schupstraat 1, 2018 Antwerp, BELGIUM
The American Gem Society laboratory was established in 1996 to provide modern diamond grading services for the diamond marketplace. It is also highly respected worldwide. AGS was the first laboratory to provide a cut grade for round stones, pre- dating the GIA. In addition it pioneered some other innovations. AGS uses a unique 0 to 10 grading system to quantify diamond colour, clarity, and cut. A grade of 0 indicates the rarest, most desirable quality, a 10 rating is the least desirable. Each number corresponds to the internationally accepted GIA diamond scale nomenclature.
Again, the methodology of grading the stones is very similar to the three other laboratories, with measurements and weights being read, stones being analysed by a team of gemologists and later randomly checked by senior gemologists. In addition, AGS evaluate a few other criteria such as light performance, proportion factors and finish.