Podcast
Questions and Answers
What is the most important factor in determining a stone's desirability, marketability, and value?
What is the most important factor in determining a stone's desirability, marketability, and value?
What type of reactions can treatment alter or initiate in gems?
What type of reactions can treatment alter or initiate in gems?
What is white light composed of?
What is white light composed of?
What is the primary cause of selective absorption in gems?
What is the primary cause of selective absorption in gems?
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What type of gems can exhibit pleochroism?
What type of gems can exhibit pleochroism?
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What causes the most desirable red and green gem colors?
What causes the most desirable red and green gem colors?
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What is the effect of heat treatment on unwanted colors in gems?
What is the effect of heat treatment on unwanted colors in gems?
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Which element causes a greater variety of gem colors than any other?
Which element causes a greater variety of gem colors than any other?
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What is the relationship between dispersion and RI in gems?
What is the relationship between dispersion and RI in gems?
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What is the result of irradiation in gems?
What is the result of irradiation in gems?
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" RI " or Refractive index is described as ...?
" RI " or Refractive index is described as ...?
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What cause the same trace element to produce different colors in different gems ?
What cause the same trace element to produce different colors in different gems ?
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What is the primary source of radiant energy that travels in waves?
What is the primary source of radiant energy that travels in waves?
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What is the role of transition elements in a gem's band gap, helping electrons absorb some visible light wavelengths?
What is the role of transition elements in a gem's band gap, helping electrons absorb some visible light wavelengths?
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What is the effect of chemical composition and crystal structure on gem color?
What is the effect of chemical composition and crystal structure on gem color?
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What is the result of interaction between electrons and visible light in gems?
What is the result of interaction between electrons and visible light in gems?
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What is the purpose of heat treatment in gems?
What is the purpose of heat treatment in gems?
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What is the characteristic of gems that can exhibit pleochroism?
What is the characteristic of gems that can exhibit pleochroism?
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What is the result of valence differences in the same gem material?
What is the result of valence differences in the same gem material?
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What is the relationship between dispersion and refractive index in gems?
What is the relationship between dispersion and refractive index in gems?
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What is the cause of colors produced by charge transfer in gems?
What is the cause of colors produced by charge transfer in gems?
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What is the role of irradiation in gems?
What is the role of irradiation in gems?
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Study Notes
Factors Affecting Gem Color and Value
- Color is the most important factor affecting a gemstone's desirability, marketability, and value.
- Colors produced by charge transfer are stronger than those caused by dispersed ions.
Light and Electromagnetic Spectrum
- Light is a form of radiant energy that travels in waves.
- Visible light is a small portion of the electromagnetic spectrum.
- White light is a combination of spectral colors: red, orange, yellow, green, blue, and violet.
Gem Color and Absorption
- Most gem color is caused by selective absorption, influenced by chemical composition and crystal structure.
- Interaction of electrons with visible light causes most selective absorption related gem colors.
Transition Elements and Color Centers
- The presence of transition elements adds new energy levels within a gem's band gap, enabling electrons to absorb specific wavelengths.
- Color centers allow selective absorption to take place by lowering the energy required for electron transitions.
- Chromium causes the most desirable red and green gem colors.
- Iron causes a greater variety of gem colors than any other transition element.
Treatment and Pleochroism
- Heat treatment removes unwanted colors by destroying color centers.
- Only doubly refractive gems can be pleochroic.
- Valence differences can cause variations in color intensity in the same gem material.
Dispersion and Refractive Index
- Dispersion is greater in high-RI gems than in low-RI gems.
Factors Affecting Gem Color and Value
- Color is the most important factor affecting a gemstone's desirability, marketability, and value.
- Colors produced by charge transfer are stronger than those caused by dispersed ions.
Light and Electromagnetic Spectrum
- Light is a form of radiant energy that travels in waves.
- Visible light is a small portion of the electromagnetic spectrum.
- White light is a combination of spectral colors: red, orange, yellow, green, blue, and violet.
Gem Color and Absorption
- Most gem color is caused by selective absorption, influenced by chemical composition and crystal structure.
- Interaction of electrons with visible light causes most selective absorption related gem colors.
Transition Elements and Color Centers
- The presence of transition elements adds new energy levels within a gem's band gap, enabling electrons to absorb specific wavelengths.
- Color centers allow selective absorption to take place by lowering the energy required for electron transitions.
- Chromium causes the most desirable red and green gem colors.
- Iron causes a greater variety of gem colors than any other transition element.
Treatment and Pleochroism
- Heat treatment removes unwanted colors by destroying color centers.
- Only doubly refractive gems can be pleochroic.
- Valence differences can cause variations in color intensity in the same gem material.
Dispersion and Refractive Index
- Dispersion is greater in high-RI gems than in low-RI gems.
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Description
This quiz explores the importance of color in gemstones, how it affects their value, and the role of light in understanding color-causing reactions.
