This response is written to address the article The Effect of Indexed Upper Half Facets written by Mr. Peter Yanzer. The opening paragraph of the article presents a concept that indexing top halves produces different amount of weight retention. This is correct, although not as dramatic as presented. A diamond cut...
by Peter Yantzer, CG American Gem Society Laboratories Gemstone cutters can tilt or 'index' the upper half ( or upper girdle ) facets. This indexing produces different amounts of weight retention from a given piece of rough and produces different optical performance effects. Indexing can also affec...
The Effects of Indexed Upper Half Facets CLICK HERE TO VIEW POST
In the course of this first quarter of 2005, AGS will launch new grading reports for princess-cuts. For the first time in the history of diamonds and grading labs, there will be a cut-grade on a fancy shape. While we are preparing and cutting some princesses in order to get a 0-grade, we are amazed by the major c...
AGS’ new cut-grading of princesses: a first experience CLICK HERE TO VIEW POST
Most jewelers and diamond dealers have for decades shared in a system called memorandum or memo. If a customer goes into a store looking for a particular item that the store doesn’t have in stock at the moment, they will ring up one their suppliers and borrow a few stones for long enough to make a sales presentation...
Why are there several dealers offering the exact same stone? CLICK HERE TO VIEW POST
As some industry leaders are fond of pointing out, a non-H&A diamond can be just as bright under direct lighting as some H&A diamonds. I agree. But that is not the whole story when it comes to H&A diamonds... After all, most people don't carry a set of halogen lights to shine on their diamond at ...
Hearts & Arrows Diamonds – It’s not all about light return. CLICK HERE TO VIEW POST
Market of rough diamonds The first major event of the year was last week’s overall 3% price increase by De Beers’. On top of that, sightholders are looking at an extra charge of probably 2%, in order to contribute to De Beers’ promotional budget. All together, this is already an overall increase of over 5...
The AGA-LBI and DFS System With the advent of new technology which is capable of physically measuring light behavior in diamonds, AGA will now use the new AGA Durability-Finish-Size (DFS) system when we also utilize ImaGem light measurements. The original AGA Cut Class system was based on a conservative and tradi...
The NEW AGA Cut Class and AGA-Light Behavior Index with ImaGem CLICK HERE TO VIEW POST
Contrast A chess board is 50% black; it returns half as much light as a sheet of white paper. But a chess board looks brighter than white paper when they are both moving. The same is true for a diamond; if a stone returned light so that the crown was bright all over, it would not appear as bright to your ...
The role of contrast in diamond appearance CLICK HERE TO VIEW POST
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