Ass #6 -Nature of Light and Gem Colorations
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Questions and Answers

What type of defects are primarily responsible for causing green color in diamonds?

  • Hydrogen-related defects
  • Boron-related defects
  • Carbon-related defects
  • Nickel-related defects (correct)

Which colors in diamonds are associated with the presence of hydrogen-related defects?

  • Brown and Black
  • Red and Pink
  • Blue, Violet, and Gray (correct)
  • Green and Yellow

How does radiation exposure affect diamond color, specifically in relation to the Dreseden Green diamond?

  • It causes a uniform blue color
  • It creates a uniform green color (correct)
  • It enhances yellow hues
  • It results in a pink hue

Which of the following diamond colors is primarily caused by deformation, particularly in the region around 550 nm in the visible spectrum?

<p>Pink to Red diamonds (A)</p> Signup and view all the answers

What happens to chameleon diamonds when subjected to heat or darkness for an extended period?

<p>They temporarily lose their green color and change to yellow or orange (B)</p> Signup and view all the answers

What type of diamonds are classified as type IIb, and what causes their color?

<p>Diamonds with boron atoms replacing carbon atoms (C)</p> Signup and view all the answers

What phenomenon creates colored lamellae in pink, red, purple, and brown diamonds?

<p>Deformation resulting in closely spaced grain lines (A)</p> Signup and view all the answers

Which diamond is known for its historical significance and was once part of the collection of Henry Philip Hope?

<p>The Hope diamond (C)</p> Signup and view all the answers

What primarily causes the color in diamonds?

<p>Defects or imperfections in the crystal lattice (A)</p> Signup and view all the answers

Which type of defect in diamonds is specifically associated with color changes?

<p>Color centers (A)</p> Signup and view all the answers

How does nitrogen influence the color of diamonds?

<p>It can produce a yellowish color in diamonds (C)</p> Signup and view all the answers

What is the effect of radiation on diamond color?

<p>It can create color centers that influence color (D)</p> Signup and view all the answers

Which of the following statements is true regarding selective absorption?

<p>It allows some colors to transmit according to the diamond's defects (D)</p> Signup and view all the answers

What range of the electromagnetic spectrum can the human eye detect?

<p>400 nm to 700 nm (B)</p> Signup and view all the answers

What instrument is used to analyze the absorption spectrum of diamonds?

<p>Spectroscope (C)</p> Signup and view all the answers

What happens to the color components of light that are not absorbed by the diamond?

<p>They are transmitted and detected by the eye as color (C)</p> Signup and view all the answers

What role does nitrogen play in affecting the color of diamonds?

<p>Nitrogen creates a step in the band structure, allowing electrons to absorb light and produce color. (C)</p> Signup and view all the answers

Which of the following accurately describes the GR1 defect in diamonds?

<p>It relates to a defect caused by general radiation effects. (B)</p> Signup and view all the answers

How do defects in diamonds influence the light absorption and resulting color?

<p>Defects provide new paths for electrons to transition, leading to different colors. (A)</p> Signup and view all the answers

What effect does a radiation-generated defect have on diamond color?

<p>It can produce green or blue colors depending on the nitrogen content. (D)</p> Signup and view all the answers

What is the band gap in the context of diamond's electronic band structure?

<p>The energy difference separating the valence band from the conduction band. (B)</p> Signup and view all the answers

What distinguishes an insulator diamond from a colored diamond?

<p>Colored diamonds have added defects that allow light absorption. (A)</p> Signup and view all the answers

Which statement is true regarding the electronic transitions in diamonds with defects?

<p>Transitions can occur between the valence band, conduction band, and newly introduced defect levels. (D)</p> Signup and view all the answers

Which of the following accurately categorizes materials based on their band structure?

<p>All materials are classified into insulators, semiconductors, and conductors based on their band structure. (C)</p> Signup and view all the answers

Which of the following statements about the rarity of diamond colors is true?

<p>Pure red and pure purple diamonds are among the rarest. (B)</p> Signup and view all the answers

What effect does long-term radiation exposure have on the color of diamonds, specifically referring to the Dreseden Green diamond?

<p>It creates a uniform green color. (A)</p> Signup and view all the answers

Which type of diamond is categorized as type IIb?

<p>Diamonds with pure blue color due to boron substitution. (D)</p> Signup and view all the answers

What characteristic is associated with chameleon diamonds after being heated or kept in darkness?

<p>They temporarily lose their green color. (A)</p> Signup and view all the answers

Which cause primarily contributes to the pink and red colors in diamonds?

<p>Deformation correlated with an absorption band around 550 nm. (D)</p> Signup and view all the answers

Why are nickel-related defects less common in colored diamonds?

<p>Nickel atoms are too large and complicate the lattice structure. (D)</p> Signup and view all the answers

What characteristic color change occurs in blue diamonds due to hydrogen-related defects?

<p>They display gray subtones. (D)</p> Signup and view all the answers

Which diamond is associated with the historical figure Louis XIV?

<p>The Hope diamond. (B)</p> Signup and view all the answers

What causes the highly saturated yellow or orange-yellow color in diamonds often referred to as 'canary' diamonds?

<p>Isolated nitrogen atoms causing absorption in the ultraviolet region (D)</p> Signup and view all the answers

Which defect is primarily associated with pure green diamonds resulting from radiation exposure?

<p>General Radiation 1 (GR1) defect (B)</p> Signup and view all the answers

How do Type Ib diamonds differ from Type Ia diamonds in terms of nitrogen content?

<p>Type Ib diamonds contain smaller concentrations of nitrogen impurities than Type Ia (D)</p> Signup and view all the answers

What is the primary cause of yellow body color in type Ia diamonds?

<p>Absorption of blue light due to nitrogen defects (D)</p> Signup and view all the answers

What effect do higher concentrations of nitrogen impurities have on the body color of diamonds?

<p>They may result in an orangy body color (A)</p> Signup and view all the answers

Why are green stones with saturated colors considered rare and sought after?

<p>Natural radiation exposure is infrequent (C)</p> Signup and view all the answers

Which condition describes the visual signs of radiation damage on a diamond's surface?

<p>Patches of color referred to as staining (D)</p> Signup and view all the answers

Which of the following is a well-known diamond in the orange color range?

<p>Pumpkin Diamond (A)</p> Signup and view all the answers

What specific type of defect can lead to the blue color in diamonds?

<p>Boron replacing carbon in the lattice (A)</p> Signup and view all the answers

Which factors can influence the color of diamonds caused by radiation-generated defects?

<p>Concentration of defects and presence of nitrogen (B)</p> Signup and view all the answers

What primarily distinguishes Type Ib diamonds from other types?

<p>They are characterized by a specific range of color caused by nitrogen defects. (D)</p> Signup and view all the answers

What happens to electrons in diamonds when they absorb visible light?

<p>They move from the valence band to the higher energy conduction band. (B)</p> Signup and view all the answers

What is a defect that can cause yellow color in diamonds?

<p>The presence of nitrogen impurities at specific concentrations (D)</p> Signup and view all the answers

What role does the band gap play in the properties of diamond?

<p>It separates the valence band from the conduction band, affecting color absorption. (B)</p> Signup and view all the answers

How does the presence of defects in diamonds lead to different colors?

<p>Different types of defects interact with light in varying ways, changing the perceived color. (D)</p> Signup and view all the answers

What is a characteristic of a defect-free diamond?

<p>It is transparent and colorless as it does not absorb visible light. (B)</p> Signup and view all the answers

Flashcards

Visible Light

A small part of the electromagnetic spectrum that human eyes can detect.

Wavelength

The distance between two consecutive points along a wave.

Selective Absorption

The process where a material absorbs some colors of light and reflects others.

Electromagnetic Spectrum

The entire range of radiant energy, from high to low energy.

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Absorption Spectrum

A way to see which colors a material absorbs by splitting white light.

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Color Centers

Defects in a crystal lattice causing a diamond's color.

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Spectroscope

A device that separates white light into its spectral colors.

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Gem Color

Result of selective absorption and transmission that are not absorbed.

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Excited State

A higher energy level temporarily occupied by an electron after absorbing specific light.

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Transition (in electrons)

The process of an electron returning to its stable energy level (ground state) while releasing energy.

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Band Gap

The energy difference between the valence and conduction band in a solid material.

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Valence Band

The band of lower energy levels occupied by electrons in a solid material

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Conduction Band

An energy band higher than the valence band, typically containing free electrons.

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Insulator (material)

A solid material with a large band gap, preventing the flow of electrons.

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Defect (in a crystal)

An imperfection or irregularity in the arrangement of atoms in a crystal lattice.

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Color center (in diamond)

A defect in a diamond's crystal structure that absorbs specific wavelengths of light, causing color.

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Red-end Absorption

Defects related to hydrogen in diamond cause absorption of red light, leading to colors beyond the visible spectrum.

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Green Diamond Defect

Nickel-related defects cause green color, but they are less common due to nickel's size, which is difficult to accommodate in the diamond lattice.

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Type Ia Green Diamonds

Green diamonds colored by hydrogen, nickel, or nitrogen defects are categorized as Type Ia diamonds.

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Dresden Green

A rare 41-carat diamond with a uniformly green color, likely caused by prolonged exposure to radiation.

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Chameleon Diamonds

These diamonds temporarily lose their green color and turn yellow or orange when heated or left in the dark, a phenomenon not fully understood.

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Blue Diamond Color

Blue diamonds are rare and usually have a slight gray tint, caused by boron atoms replacing carbon in the crystal lattice.

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Type IIb Blue Diamonds

Diamonds with a pure blue color are classified as Type IIb.

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Deformation in Pink & Red

Pink, red, purple, and brown diamond colors are often caused by deformation in the lattice, leading to an absorption band around 550 nm.

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Hydrogen-related defects

These imperfections in the diamond's structure absorb red light and beyond, causing the diamond to appear colorless or with shades of yellow or brown.

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Nickel-related defects

These defects are uncommon because nickel atoms are large and difficult to fit into the diamond's structure. They cause green color in diamonds.

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Green Diamonds: Type Ia

Green diamonds colored by hydrogen, nickel, or nitrogen defects are classified as Type Ia diamonds.

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Dresden Green: Rare Color

The Dresden Green is a famous 41-carat diamond with a unique, consistent green color, believed to be caused by long-term exposure to radiation.

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Chameleon Diamonds: Color Change

These diamonds lose their green color and become yellow or orange when heated or left in darkness for a while. The exact reason for this color change is still unclear.

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Blue Diamond: Boron

The blue color in diamonds is caused by boron atoms replacing carbon atoms in the crystal structure. Most blue diamonds have a slight gray tint.

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Pink and Red Diamonds: Deformation

The pink, red, purple, and brown colors in diamonds are often caused by deformation in the crystal structure, resulting in an absorption band around 550 nm.

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Insulator

A material with a large band gap, preventing electrons from flowing easily.

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Defect

An imperfection in the arrangement of atoms in a crystal lattice.

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Nitrogen Impurity

A nitrogen atom replacing a carbon atom in the diamond's structure, causing a yellow color.

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Boron Impurity

A boron atom replacing a carbon atom, creating a step in the diamond's band gap, leading to blue color.

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Radiation-generated Defect

A defect caused by exposure to radiation, influencing color based on nitrogen content.

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What causes yellow diamonds?

Yellow diamonds are primarily due to the presence of nitrogen impurities within the diamond's structure. These nitrogen atoms can be in various combinations, like three nitrogen atoms adjacent to a vacancy (N3 center) or isolated nitrogen atoms (C centers).

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Type Ia vs. Type Ib diamonds

Type Ia diamonds have a higher concentration of nitrogen than Type Ib diamonds, resulting in a more saturated yellow color. Type Ib diamonds, with fewer nitrogen atoms, can have a pale yellow or orange-yellow hue.

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Cape Diamonds

Natural yellow diamonds colored by the N3 defect are often referred to as 'cape' diamonds in the trade.

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Canary Diamonds

Canary diamonds are a type of yellow diamond with a highly saturated yellow or orange-yellow hue, caused by isolated nitrogen atoms (C centers).

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What causes green diamonds?

Green diamonds are often formed through exposure to radiation over long periods. This radiation creates 'General Radiation 1' (GR1) defects, absorbing red light and resulting in a green color.

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Green diamond variations

Green diamonds can be pure green, yellow-green, or mixed with other colors like blue, brown, or gray. Pure green stones with a saturated color are considered rare and valuable.

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Radiation stains

Direct contact with radioactive minerals can cause patches of green or brownish color on the diamond's surface, known as radiation stains.

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Other green diamond color centers

Some green diamond colors result from hydrogen and nickel impurities within the diamond's structure.

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Study Notes

Nature of Light

  • Light is electromagnetic energy, traveling in waves.
  • Wavelengths are measured in nanometers (nm).
  • Shorter wavelengths have higher energy; longer wavelengths have lower energy.
  • Visible light is a small portion of the electromagnetic spectrum, ranging from 400nm (violet) to 700nm (red).

Selective Absorption

  • White light is a combination of all visible colors.
  • Gem materials selectively absorb certain wavelengths of light.
  • Transmitted light determines the gem's apparent color.
  • Diamonds' color is primarily due to imperfections in their crystal structure.

Color Centers

  • Color centers are defects in a crystal lattice.
  • Defects cause absorption of specific wavelengths, affecting the diamond's color.
  • Not all defects result in colored diamonds.

Absorption Spectrum

  • A spectroscope separates white light into its spectral colors.
  • An absorption spectrum shows which colors a diamond absorbs.
  • A spectrometer provides a precise graph of absorption/transmission.

Atoms, Electrons, and Energy Levels

  • Electrons play a crucial role in selective absorption.
  • Electrons absorb light energy, moving to higher energy levels (excited states).
  • Energy is released when electrons fall back to ground state, emitting light.

Band Structure of Diamond

  • Electronic band structure explains properties of solids.
  • Electrons in a valence band can move to a conduction band with sufficient energy.
  • A band gap separates valence and conduction bands.
  • Defect-free diamonds are insulators.

Causes of Color in Diamonds

  • Defects act as "steps" in the band gap, affecting electron transitions.
  • Nitrogen and boron impurities are common color centers.
  • Defects can create different colors depending on concentration and other defects.
  • Radiation-generated defects can produce green or blue.

Naming Defects

  • Defect names often describe the cause or a general type.
  • Examples: GR1, N1, N2, H1, etc.
  • Some defects appear in natural diamonds and those heated.

Yellow and Orange Diamonds

  • Nitrogen is a primary cause of yellow color.
  • Different nitrogen concentrations and types result in varying shades.
  • Imperfections in the crystal lattice contribute to orange colors in some diamonds.

Green Diamonds

  • General radiation (GR1) defects can cause green colors.
  • Nitrogen-related defects are associated with green-blue to blue diamonds.
  • Radiation damage can produce stains on diamond's surface.
  • Hydrogen- and nickel-related defects can also cause green.

Blue, Violet, and Gray Diamonds

  • Boron impurities are associated with blue diamonds.
  • Hydrogen-related defects may affect blue, violet, and gray.
  • The color is often a combination of different components.

Pink, Red, Purple, and Brown Diamonds

  • Pink and red are among the rarest.
  • Color is often related to concentrated absorption bands.
  • Vacancies, nitrogen atoms, and deformations.
  • The color is also a result of intense radiation damage.

Black, Gray, and White Diamonds

  • Inclusions, such as graphite and other minerals, contribute to black colors.
  • Micro-inclusions and other defects cause gray and white colors.

Luminescence

  • Luminescence is the emission of light from gems.
  • Some diamonds fluoresce (emit light) under UV light.
  • Phosphorescence continues light emission after the radiation stops.
  • Luminescence identifies defects and helps in diamond identification.

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ASS #6 Diamond & Color PDF
ASS #6 Diamond & Color PDF

Description

Explore the fascinating relationship between light and the colors of gemstones in this quiz. Understand how light behaves as electromagnetic energy and how selective absorption influences the apparent colors of gems like diamonds. Test your knowledge on wavelengths and color centers in crystals.

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