Gemstone usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons. Gemstones are classified into different "groups", "species", and "varieties". For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl. Gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. They may exhibit pleochroism or double refraction. They may have luminescence
Aquamarine (novel) from her six sisters, and is suffering from the chlorine in the pool. Hailey and Claire advise Aquamarine to return to the ocean, however she refuses, because of her new attachment to Raymond. Claire and Hailey read books that contain information pertaining to marine life-forms, trying to find an answer to Aquamarine's troubling conditions. They learn that mermaids cannot survive on land for more than a week. The necessity of returning Aquamarine to the ocean is thus made more urgent. In order to persuade Aquamarine to return to her home, Hailey and Claire arrange that she will spend one evening