what are blue semi precious stones?
['Sapphire. By far the most popular blue gem for faceting, a blue sapphire can have very high saturation. ... ', 'Tourmaline (Indicolite and Paraíba) ... ', 'Aquamarine. ... ', 'Spinel. ... ', 'Turquoise. ... ', 'Chalcedony. ... ', 'Jeremejevite. ... ', 'Dumortierite.']