Gemstones
Notes On Specific Gravity
Notes On Specific Gravity Copyright © Charles Lewton-Brain 1986 – 1994 Archimedes is said to have discovered that when a body is placed in water the volume of water displaced is equal to the volume of the body and that when the body is placed in water that it undergoes an apparent loss of weight. [...]
Read Full Post | Make a Comment ( None so far )Physical Properties of Gemstones
Introductory Gemmology – Definitions Concerning Physical Properties of Gemstones Copyright © Charles Lewton-Brain 1997 Crystal Structure A perfect crystal is bounded by plane faces which meet at angles specific for each kind of material (angle analysis can identify minerals). A crystal may be cleaved in directions related to the external form or to a possible [...]
Read Full Post | Make a Comment ( None so far )Basic Optics Notes for Gemology
Basic Optics Notes for Gemology Copyright © Charles Lewton-Brain 1986 -1994 The optical characteristics and properties of gemstones often provide the fastest and best methods of identification. A certain amount of theory is necessary as optical principles determine cutting methods, gemstone attributes and the function of gem testing instruments. Light Light and our perception of [...]
Read Full Post | Make a Comment ( None so far )Properties of light and Gemstones
Article by: Mr. Englisher – Gemcal.com Notes about colors The colors of gemstones slightly vary when exposed to different light sources. Any light source has a specific spectral quality. Further variations are accruing when gemstones are photographed, and their images are transmitted and displayed through different types of electronic devices. Minor color differences between an [...]
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