(IDEX Online) - A diamond exhibiting two distinctly different colors has been described by expert gemologists at GIA as unique.The 0.63-ct tapered baguette-cut natural diamond is part Fancy Dark orangy brown and part Fancy Dark brown greenish yellow. It "demonstrates the variety possible within the natural world," say Mei Yan Lai and Sally Eaton-Magana, authors of an article entitled Rare Natural Bicolor Diamond in the latest edition of GIA's Lab Notes.The gem was submitted to GIA at the Tucson Gem, Mineral & Fossil Showcase 2023."The brown greenish yellow zone had chameleon properties, including a temporary color change upon heating or when left in darkness for an extended period of time (possibly days)."They say bicolor diamonds are very uncommon, and the colors likely result from a combination of lattice defects.The diamond has alternating blue and greenish yellow fluorescence zones, though they do not correlate with the major color zoning (i.e., orangy brown and brown greenish yellow).Pic by Adriana Robinson.