Gems & Gemology, Winter 2009, Volume 45, No. 4
Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds
Al Gilbertson, Benjamin Gudlewski, Mary Johnson, George Maltezos, Axel Scherer, and James Shigley
A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond. These Nanocut plasma-etched diamonds can be identified with magnification by the presence of small, unpolished-appearing areas on the facets where the grating pattern has been created. Round brilliant–cut diamonds displaying such patterns will be classified by the GIA Laboratory as modified round brilliants; as such, they will receive color and clarity grades, but not a cut grade.