Owning a gemstone is holding a piece of the universe.
But to understand gemstones, it can take years of study.
What makes it beautiful?
Gemology is the science dealing with natural gemstones. It is considered geosciences. Knowledge in chemistry, crystallography, mineralogy, and in physics, including optical.
The identification of gemstones is a forensic science, which requires the collection of data followed by a detailed analysis of it. Rather than look for the similarities between gemstones, we look for the unique properties and characteristics that make them different, which included the identification of a natural gem vs. lab-created
The Solar Spectrum In 1802, the English chemist William Hyde Wollaston was the first person to note the appearance of a number of dark features in the solar spectrum. Twelve years later, Joseph Fraunhofer (1787–1826), during an independent study, rediscovered the lines in the solar spectrum and began a systematic study including a careful measurement of the wavelengths of these dark (absorption) lines. In all, he mapped 574 lines and designated the principal features with the letters A through K. The weaker lines were assigned other letters. We now refer to these lines as the Fraunhofer lines. Fraunhofer deduced that these dark lines were segments of colors (wavelengths of visible light) absorbed by cooler gases present higher in the Sun’s atmosphere but originally emitted by the hotter gases lower in the Sun’s atmosphere.
Today, using far more sophisticated techniques; astronomers have discovered tens of thousands of Fraunhofer lines.
Four properties of light relevant to gemology
Intensity
Propagation direction
Frequency or wavelength spectrum
Polarization.
Light travels at a speed of 186,282 miles per second (299,792 kilometers per second), and until recently was considered one of the fundamental constants of nature.
We now know that all objects absorb or reflect certain wavelengths of light and depending on its chemical composition(s), and reacts according to the type of light source. In some cases, a change of light source can also result in a perceivable change in color.
Alexandrite for example, with a broad absorption band in the yellow portion of the spectrum, appears green in daylight since daylight is rich in shorter wavelengths, and red under a blue-deficient tungsten lamp, which is richer in longer wavelengths. This property is known as METAMERISM.
Allochromatic Gemstones: Gemstones where their color is caused by impurities.
Idiochromatic Gemstones: Gemstones that owe their color to elements present in their chemical composition. Selective absorption of light in both Allochromatic and Idiochromatic gems is caused mainly by the presence of any of the transition metallic elements from the periodic table of elements.
The Absorption of Light and The Spectroscope
Transition Metallic Elements Energy level consists of varying types of orbitals; however, in the case of the transition metallic elements, it is the partially filled
d-orbitals, which contain in some cases unpaired electrons that are of the most interest. If light of a wavelength, with appropriate energy to raise an electron to a higher energy state, is completely absorbed by the electron, it will result in that particular wavelength being removed from the spectrum through absorption. When the electron returns to its original state, the excess energy is emitted as heat. The energy that is required to raise the energy of an unpaired electron to a higher energy state and cause absorption is far less than the energy required to raise a paired electron. While the energy in visible light is insufficient to raise a paired electron in the other orbitals, it can raise the unpaired electrons that reside in the
d-orbitals of the transition metallic elements. This is why transition elements are also referred to as coloring elements or coloring agents. There are also some rare earth elements that can act as gemstone coloring elements.
Reaction to light
What is Fluorescence? A reaction to a certain energy, a glow when exposed to a UV light, an effect observed instantly.
What is Phosphorescent? When a gemstone temporarily stores the absorbed light (energy) for a longer time and temporarily retains its luminosity from within as electrons gradually and through vibrations, slowly move back to their original orbits, after the source has been turned off.
THERMOLUMINESCENCE
Thermoluminescence is the ability of a mineral to emit a small amount of light upon being heated
TRIBOLUMINESCENCE
Some minerals will emit light when they are struck, crushed or scratched
Color Centers: Gemstone color can also be produced by color centers that are caused by defects within the crystal lattice. These defects, which can be caused by natural or artificial radiation, are the result of either an extra trapped electron or an electron missing from a site in the crystal lattice. This results in an extra electron at a site where it would normally not occupy or an extra space or hole in the lattice. The extra electron creates an electron color center, while the missing electron creates a hole color center. Color centers are commonly found in fancy color diamonds where the radiation is a result of the natural geological crystal growth environment, irradiated diamonds, and topaz.
Why NASA Scientists Observe the Sun in Different Wavelengths
https://www.nasa.gov/mission_pages/sunearth/news/light-wavelengths.html
Are you curious to learn more about the Science of Gemology?
A FREE WORLD-CLASS COURSE IN GEMOLOGY?
The American Gem Academy
OUR COURSES COME IN 3 DIFFERENT LANGUAGES
A glimpse??? No, more than just a glimpse (100 pages to 102 pages depending on the language).
(This free course does not qualify anyone to earn a Gemology Degree nor a Certificate of accomplishment. No quizzes nor any tests – Just download and enjoy)
http://www.americangemacademy.com/
Your direct link:
https://docs.google.com/forms/d/e/1FAIpQLScxzOz_tGd8M2U4qlw5RYfPauKN4szpcmGUFnfpcSzy8UVfqw/viewform
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Sincerely,
Jack Ghazalian
Director of Corporate & Career Development USA
