542 



REPORT OF NATIONAL MUSEUM, 1900. 



III. — f'omparatirc Uthlix of tlic colors and distinguisJmig rhdractn-s of the heller-hiown 



gems — Continued. 



VIII.— BLUE STONES. 



IX.— VIOLET OR AMETHYSTINE STONES. 



Sapphire (orien- 

 tal amethyst). 

 Garnet , 



Spinel 



Diamond 



Tourmaline 



Quartz ( ii ni e - 

 thy.st). 



3. 97-4. 27 



3. 5 -4. 3 



3.5 -3.8 



3. 48-3. 52 

 2. 99-3. 22 

 2. 55-2. 7 



6.5-7.5. Varies, 

 but in general 

 is above 7. 



8 



10.... 



7-7.5 . 

 7 



Double. 



Single. 



Single. 

 1.810. 

 Single. 

 Double. 

 Double. 



Sec previous tables. 

 Do. 



Do. 

 Do. 

 Do. 



X.— BLACK-COLORED STONES. 



