สำนักราชบัณฑิตยสภา

The Journal of the Royal Institute of Thailand Vol. 27 No. 3 Jul.-Sept. 2002 A Ruby Grading System ˜Ù this study were buyers and gemo- logists from various countries who attended the 28th Gem and Jewel- ry Fair in Bangkok between the 13th and 16th of September 2001. The participants were divided into six groups and numbered by geo- graphic origin (Thais 191, Ameri- cans 49, Europeans 76, Japanese 55, Indians 64, and other Asian countries 47). The results of the Color Preference Survey are shown A flowchart showing criteria used to assess a rubyûs grading Subjective method Objective method (Visual sensation & experience) 1. Beauty 2. Quality 3. Value Attractive color Natural or synthetic origin Brilliance Treatment Transparency Country of origin Color grading Clarity grading Cut grading Carat weight Hue/Tone/Saturation Inclusion Proportion/Finish - Position Dark red - Amount Excellent Deep red - Size Fine Vivid red - Aggregation Very good Strong red - Contrast Good Pinkish red Fair Purplish red Excellent clarity/minute inclusion (Mil) Fine clarity/minor inclusion (MrI) Very good clarity/noticeable inclusion (NI) Good clarity/moderate inclusion (MI) Fair clarity/significant inclusion (SI) ➤ ➤ ➤ Diagram 1 Fig. 4 Two sets of Thai, Mong Hsu Mogok and Madagascar rubies