Gemmology, Third Edition by Peter Read C Eng MIEE FGA DGA

By Peter Read C Eng MIEE FGA DGA

Due to the fact Gemmology was once first released, hundreds of thousands of readers have used it to achieve an in-depth appreciation of the technological know-how of gemmology, its historical past and perform. This 3rd version has been revised to hide, particularly, This 3rd version has been revised to hide, specifically, new HPHT diamond enhancement equipment and beryllium lattice diffusions ideas for corundum in addition to the low strain extreme temperature CVD synthesis of thick movie diamond It contains information of the Gemmological institutions lately brought starting place path, and offers exam notes. * comprises crucial details for the Gem-A checks * absolutely up-to-date to hide fresh advances and tools * a useful source for gemmologists around the globe

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This unbalances the atomic charges and results in a positively charged sodium ion and a negatively charged chlorine ion, the opposite charges producing the ionic bonding force of attraction charge (Naϩ). Atoms which are no longer electrically neutral are known as ions. A positive ion is called a cation. In acquiring an extra electron to add to its existing seven, the chlorine atom becomes negatively charged (ClϪ). This type of ion is called an anion. As exactly the same number of electrons have been both donated and acquired, the overall electrical charge again becomes neutral.

Atoms which are no longer electrically neutral are known as ions. A positive ion is called a cation. In acquiring an extra electron to add to its existing seven, the chlorine atom becomes negatively charged (ClϪ). This type of ion is called an anion. As exactly the same number of electrons have been both donated and acquired, the overall electrical charge again becomes neutral. However, it is the electrical force of attraction that exists between the positive cation and negative anion ions in the compound that produces the bond between them.

For most practical gemmological work it is only necessary to be able to recognize the habits of the various gem crystals and to be aware of their individual optical and physical characteristics. However, the student of gemmology should also be familiar with the convention of imaginary crystallographic axes which are used to describe the idealized shape of a crystal. Of equal importance are the three elements of symmetry, as they include axes of symmetry which alone define the seven crystal systems.

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