Articles about Diamond Grading

Laboratory Cut Grades: What the report doesn’t show

What the report doesn’t show

 

To the naked eye a D Flawless diamond can appear identical to an F VS diamond if each has been cut the same way.  Alternately, less than one degree of variation in two diamonds’ facet measurements can make a noticeable difference in appearance - yet both could be issued the same cut grade from a given lab.

60/60 or ideal cut. How do you know what to choose?

Recently, I had the opportunity to examine two very similar diamonds, one cut to near Tolkowsky ideal AGS0 specifications and one cut to near what dealers refer to as 60/60 make. 60/60 refers to 60% table, 60% depth. Diamond dealers would consider both of these cut styles as very good cutting, but the ideal spec stone has a distinct advantage in the Internet marketplace. It got me thinking about why that is the case. Both of these diamond looked very good and not all that different than one another. Why does one, the ideal cut, hold such an advantage?

Buying Diamonds: Consumers’ Problems and a Solution

Buying Diamonds:

Consumers’ Problems and a Solution

By Sergey Sivovolenko, Janak Mistry, Garry Holloway and Dr Yuri Shelementiev

Do the pavilion mains drive light return in the modern round brilliant?

On many websites you will see it said that the pavilion main facets drive light return. Top labs and many grading systems use the pavilion angle as a basis for assigning a cut grade.

Is this correct?

A screening tool for all diamond grading

"Levels of Confidence"
A pre-purchase, screening tool for the consumer. An explanation tool for the appraiser.
Intended to gauge the credibility of represented color, clarity and cut grades compared to GIA or AGSL grading.
Highest Confidence: SCORE = 1
The grade will exactly match GIA/AGS 65% to 70% of the time. This is about the level at which these lab’s own graders match each other’s grades while working on diamonds. This grade ONLY applies to loose diamonds. Only very highly experienced, properly trained and equipped graders can claim this level of confidence. Very few gem laboratories or gemologists actually have this degree of competence.