สำนักราชบัณฑิตยสภา

«“√ “√ √“™∫— ≥±‘µ¬ ∂“π ªï ∑’Ë Ú˜ ©∫— ∫∑’Ë Û °.§.-°.¬. ÚıÙı Sakda Siripant ˜ÙÛ the ASTM color chart. Addition- ally the Munsell Color Code can be converted into the color coor- dinates of the L*U* V* and L*a*b* system** ,1 . 2.2 Clarity grading Clarity is the second most important fac- tor when evaluating rubies, i.e. when determining value and is worth between 20 and 30 per cent in the grading system. The clarity of a ruby is first determined with the naked eye and then under 10x magnification. The clarity of a ruby can be determined by a point sys- tem that takes into account the fol- lowing factors: inclusions (includ- ing the location of inclusions in the ruby), number of inclusions, the size aggregation and contrast of any inclusions. (Tables 1-2) Then, the total score will be used to assign the final clarity grade: <9 Minute inclusions (MiI) or excellent clarity 10-12 Minor inclusions (MrI) or fine clarity 13-16 Noticeable inclusions (NI) or very good clarity 17-19 Moderate inclusions (MoI) or good clarity 20 Significant inclusion (SI) or fair clarity Minute inclusion (MiI): Visible with 10x magnification, very difficult to see with the naked eye. Minor inclusion (MrI): Visible with 10x magnification, difficult to see with the naked eye. Noticeable inclusion(NI): Easily visible with 10x magnification, just able to see with the naked eye. Moderate inclusion(MoI): Very easily seen with 10x magnification, easy to see with the naked eye. Significant inclusion (SI): Very easily seen with 10x magnification, very easy to see with the naked eye. Table 1 The point system for clarity grading of rubies. Points Position Amount Relative size Aggregation Contrast 4 Table Numerous Large Dense all over Very high 3 Crown Moderate Medium Locally dense High 2 Girdle Few Small Dispersed Moderate 1 Pavilion Very few Very small Isolated Low Table 2 Sample of clarity grading Position Amount Relative size Aggregation Contrast Crown Few Medium Dispersed Low 3 2 3 2 1 Total = 11 Clarity grade : Minor inclusion (Mrl) Position Amount Relative size Aggregation Contrast Table Moderate Large Dense all over Moderate 4 3 4 4 2 Total = 27 Clarity grade : Moderate inclusion (Mol)