Apatiteis a mineral the name of which is of Greek origin. It is usually translucent and can be found in green-blue. It often displays a red iridescence and the star effect, known as asterism.
Tanzanite is the blue to violet gem variety of the mineral Zoisite (a calcium aluminium hydroxyl sorosilicate) belonging to the epidote group. It was discovered in 1967, in the Merelani Hills (Mererani) of the Manyara Region in Northern Tanzania, near the city of Arusha and Mount Kilimanjaro. Tanzanite is used as a precious stone and the naturally formed tanzanite is extremely rare and is still be mined only in the Merelani Hills.Tanzanite is also noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet and burgundy depending on the crystal orientation.Tanzanite can also appear differently when viewed under different lighting conditions. The blues appear brighter when subjected to fluorescent light and its violet hues can easily be seen when viewed under incandescent illumination. In its rough state tanzanite is colored a reddish brown and it requires heat treatment to remove the brownish “veil” and bring out the blue violet of the stone.
Aquamarine is a transparent or translucent pale blue to greenish blue mineral that was named after its color. Its name is derived from aqua (the Latin word for ‘water’) and marine (the Latin word for ‘the sea’). It is a variety of beryl, its hardness is 7.5-8, and its specific gravity is 2.75.