b'THE STATE OF RETAIL DIAMONDSJEWELRYCOLORED DESIGN STONES9 The Trade Gets a Reminder About Oiling/Filling M ost members of theIn this photomicrograph, a rubys surface-reaching cavity has been filled with red oil. (Photo credit: Billie Hughes/Lotus Gemology) trade are aware that emeralds are frequent-ly filled with oils or resins to reduce the appearance of fissures and improve clarity. Its a common and well-known process. But Lotus Gemology said its noticed an increase in the treatment in other gemstones beyond just emerald in the past five-plus years. The issue here isnt in the use of these oils or resins themselves but rather the lack of disclosure in many instances, the lab said, despite it having a big impact on a gemstones appearance. Lotus wanted to put the treatment on more trade members radars so they arentPictured at left is a caught off-guard by its presence in otherlarge tanzanite found to contain oil. The photo colored stones and know to keep an eyeat right shows how the out for it. The Thai lab has written severalhighly reflective fissures in the stone became articles about the topic and put the discus- obvious after the oil was sion in front of the gem crowd in the digitalremoved. (Photo credit: Chanon Yimkeativong/sphere, providing high-resolution imageryLotus Gemology) to demonstrate how big a difference the presence of oil or resin can make. Madagascar Pink Sapphires Get Some AttentionHeat-treating corundum to improve color and/or clarity is a practice that has been around for more than a century. While heating at high temperatures will damage most inclusions and is often detectable by gemologists, heating at low temperatures only changes inclusions slightly, requiring testing by advanced instrumentation for proper detection. Since pink sapphires from Madagascar, an important source of the material, regularly undergo low-tem-perature heat treatment, GIA studied 14 examples from Ilakaka, a small town in southwestern Madagascar, to develop criteria it could use to detect the treatment. Important findings from the study, as reported in GIAs Winter 2020 issue of Gems & Gemology, are:The subtle blue tint that occurs in many pink sapphires from Madagascar can be lightened or even removed through heat treatment at 800C (1472F); FTIR spectroscopy is vital for detecting the treatment; Monazite crystal inclusions in the material changed from orange-brown to near colorless after heating at low temperatures; andRaman spectroscopy can detect the annealing of monazite inclusions during low-temperature heating.70 STATE OF THE MAJORS 2022'