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Note: In the VVS, VS and SI grades the word imperfect is not referred to as included.

Since then, two new grades have been added to the scale. In the 1960's there was an influx of lower quality diamonds into the market. Previously, diamonds of this quality were rarely cut into gemstones and were mostly used for industrial purposes. Since the I2 grade was not defined for this lower quality, the Imperfect 3 (I3) grade was added to the scale.

By the mid-1970's, the market saw the prices of flawless diamonds increasing at an unusual pace. The price spread between Flawless and VVS1 became much larger. The laboratories began encountering diamonds free from inclusions, but with surface blemishes too obvious to be graded Flawless. This dilemma took months to resolve. Because these diamonds were still free of all internal inclusions, the Internally Flawless grade was born. The value of this grade was slightly lower than the value of the Flawless grade. Since it is extremely difficult for the cutter to attain a grade of Flawless, the Internally Flawless grade usually satisfies the diamond manufacturers. This is clearly the more common of the two grades.

The Scale Evolves

Expect that over a period of years there will be new inclusions encountered and unique opportunities to grade unusual diamonds. In the 1970's this was the case when the trade saw new inclusions in the form of reflective and whitish "raining. These diamonds were from a new source in South Africa. There was much debate about whether this type of "raining should be considered an inclusion. Finally, the GIA Gem Trade Laboratory decided that whitish, colored, and reflective "raining would be graded no higher than VVS-1. Today, laboratories often grade larger diamonds and moderately included diamonds making the slightly imperfect and imperfect ranges more difficult to grade. The trade has strongly debated the issue of eye-visible inclusions and their effect on clarity. In teaching the original system, the basic guideline was that all eye-visible inclusions were to be graded I-1 at best. Today, some larger or step cut diamonds with eye-visible inclusions may be graded SI-2 or even higher. Conversely, a diamond can have inclusions that are not visible to the unaided eye and be graded it. Liddicoat reminds us that the system he developed provided rough guidelines only, primarily for smaller stones.

Similarly there is often much discussion on borderline I grades. There are many diamond wholesalers and retailers who have created new grades to describe these borderline calls. SI-3 and VS-3 are the more popular terms used. The European Gemological Laboratory, Los Angeles, is currently the only major laboratory that uses SI-3 on their reports. The GIA system does not recognize, nor does it have any plans to add this grade. As diamond grading evolves, there is often talk of standards being relaxed or tightened. This may be true, but we must remember that many factors can influence grading. Grading is a subjective process.

Outside market factors create a changing product mix. Equipment and optics improve making it easier to see inclusions. All these factors contribute to subtle differences in the grading system without actually changing the system itself.

Split Grades

At one time, the GIA Gem Trade Laboratory used split grades on their grading reports. This was their way of describing borderline diamonds without the addition of new grades. Until the late 1970's it was common to call a diamond VS-2/SI-1 for example. The industry persuaded GIA/GTL to eliminate split grades and so only one clarity grade appears on all GIA/GTL grading reports.

It is important to note here that each clarity grade is a range of quality. Since the grade on a report appears as a single grade, it is unknown to the reader of the report, where in the range that diamond belongs. So a diamond graded SI-1 could be close to VS-2 (a "high" SI-1) or close to SI-2 (a "low" SI-1) or somewhere between (a solid SI-1). Most discussions in the laboratory are over the borderline calls. If the grader is unable to decide that the grade is a high SI-1 or a low VS-2, the diamond grader is said to be "on the fence," the border between two grades. It would be easy to give split grades again as in the old days. It is often more challenging to decide which direction to jump off of the fence.