Sapphire gemstones. Sapphires are a non-red variety of the mineral corundum (aluminium oxide). It is the second hardest mineral after diamond,rated 9 out of 10 on the Mohs scale. Although blue is the most common colour,golden,white and even black are used as gemstones. Inclusions of the mineral rutile (titanium oxide,not seen) causes a six-pointed-star light effect (asterism) to form star sapphire | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Lawry, Lawrence |
Taille de l’image : | 4200 px × 3381 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |