April Birthstone: The Diamond
We don’t talk about birthstones every single month, but we love any opportunity to talk about our favorite gemstones. Diamonds are among our favorite gemstones. The diamond is the birthstone…
Executive Director, AGS Laboratories and Gemological Sciences
Last 5 articles of this author
The Effects of Indexed Upper Half Facets
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
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...
