Assessing Diamond Value: The Four C's
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Questions and Answers

What is the standard weight of a carat in grams?

  • 0.50 g
  • 1.0 g
  • 0.2 g (correct)
  • 0.01 g

    • What is the equivalent weight of 100 points in carats?

  • 1.00 ct (correct)
  • 0.01 ct
  • 0.50 ct
  • 5.00 ct

    • How are small diamonds under approximately 0.20ct often referred to?

  • 'jewels'
  • 'giants'
  • 'melee' (correct)
  • 'titans'

    • What does a diamond graded as 'D' signify in terms of color?

    <p>Colourless - Exceptional White</p> Signup and view all the answers

    What is the method used for grading fancy colors in diamonds?

    <p>Master stones and pre-graded color comparison diamonds</p> Signup and view all the answers

    What is the main factor considered for grading fancy colors in diamonds?

    <p>The depth of color and desirability of the hue</p> Signup and view all the answers

    Which factor may make the CZ master stones less accurate for estimating the colour-group grade?

    <p>All of the above</p> Signup and view all the answers

    Why is it NOT POSSIBLE to accurately colour grade a mounted diamond?

    <p>All of the above</p> Signup and view all the answers

    What are fancy coloured diamonds graded for?

    <p>Hue, saturation, and tone</p> Signup and view all the answers

    Which factor may influence the colour of a diamond seen in daylight if it is strongly fluorescent?

    <p>All of the above</p> Signup and view all the answers

    What do we primarily grade for when using dark-field illumination/edge of the light beam during clarity grading?

    <p>Internals</p> Signup and view all the answers

    What is the nature of a 'feather' in a diamond, and how does it affect the stone?

    <p>Actual break in the stone; affects brilliance and clarity</p> Signup and view all the answers

    At which view do we primarily grade a stone from when using a 10x loupe for clarity grading?

    <p>Crown up view</p> Signup and view all the answers

    What is the highest grade on the GIA Clarity Scale?

    <p>&quot;IF&quot; - Internally Flawless</p> Signup and view all the answers

    "What is the main factor considered when grading diamonds for their fluorescence intensity under Long Wave (LWUV)?"

    <p>Intensity of fluorescence</p> Signup and view all the answers

    What are some observations used to determine the ID of a stone in non-lab testing?

    <p>Observations include lustre, cut quality, indications of hardness, girdle condition, inclusions, and surface features.</p> Signup and view all the answers

    What tests can be conducted with the Thermal conductance probe and Electrical conductance probe in non-lab testing?

    <p>The Thermal conductance probe and Electrical conductance probe can be used to test diamonds for their thermal and electrical properties.</p> Signup and view all the answers

    How does a Polariscope aid in the testing of diamonds?

    <p>Polariscopes reveal patterns in the stone, helping to determine the stone's optical nature and whether it is natural or synthetic.</p> Signup and view all the answers

    What does the Tatami strain pattern indicate in diamonds when viewed using a Polariscope?

    <p>The Tatami strain pattern indicates Type II diamonds, which could be natural, treated, or synthetic.</p> Signup and view all the answers

    How can crossed polarizing filters help in identifying synthetic diamonds?

    <p>Crossed polarizing filters can reveal strain patterns in diamonds, aiding in the identification of synthetic diamonds.</p> Signup and view all the answers

    What is the significance of plastic deformation in diamonds when viewed under crossed polars?

    <p>Diamonds with plastic deformation show high levels of strain under crossed polars.</p> Signup and view all the answers

    What are the observations for metallic inclusions in HPHT synthetic diamonds?

    <p>Hour glass/ Maltese cross colour zoning</p> Signup and view all the answers

    What are the observations for clarity treatments involving fracture filling?

    <p>Colour flashes, gas bubbles in glass</p> Signup and view all the answers

    How can laser inscriptions be identified on diamonds?

    <p>Certificate number lasered onto the girdle</p> Signup and view all the answers

    What is the purpose of the DTC DiamondSure Portable?

    <p>To identify natural diamond vs. synthetics and simulants</p> Signup and view all the answers

    How does the DTC DiamondView determine natural or synthetic diamonds?

    <p>Use of ultra-SWUV light and fluorescent patterns</p> Signup and view all the answers

    What are the distinctive growth patterns for HPHT synthetic diamonds?

    <p>Cubo - Octahedral patterns</p> Signup and view all the answers

    What types of diamonds can be detected based on their growth patterns and fluorescence?

    <p>CVD and natural Type II diamonds</p> Signup and view all the answers

    What is the basis for identifying diamond types using specialized screening equipment?

    <p>Type I diamonds absorb SWUV light, Type II diamonds transmit it</p> Signup and view all the answers

    What does the Cathodoluminescence (CL) test assess in diamonds?

    <p>Fluorescent patterns and distinctive growth patterns</p> Signup and view all the answers

    How can the presence of synthetic moissanite be detected using the DTC DiamondSure Portable?

    <p>If it does not have the absorption line at 415.2nm</p> Signup and view all the answers

    Study Notes

    Diamond Weight and Measurement

    • 1 carat is equal to 0.2 grams
    • 100 points in carats are equivalent to 0.5 carats

    Diamond Classification

    • Small diamonds under 0.20ct are often referred to as "melee"
    • A diamond graded as 'D' signifies colorless, meaning it has no detectable color

    Fancy Color Grading

    • Fancy colors in diamonds are graded using a specific method
    • The main factor considered for grading fancy colors is the hue, saturation, and tone of the diamond

    Color Grading Challenges

    • CZ master stones may be less accurate for estimating the color-group grade due to the presence of fluorescence
    • It is not possible to accurately color grade a mounted diamond because the setting can affect the appearance of the diamond

    Fancy Colored Diamonds

    • Fancy colored diamonds are graded for their intensity, hue, and saturation of color

    Fluorescence and Color

    • Strong fluorescence can influence the color of a diamond seen in daylight
    • The intensity of fluorescence is graded under Long Wave (LWUV) and the main factor considered is the strength of the fluorescence

    Clarity Grading

    • When using dark-field illumination/edge of the light beam, clarity is primarily graded for inclusions
    • A 'feather' in a diamond is a type of inclusion that can affect the stone's clarity
    • The highest grade on the GIA Clarity Scale is Flawless (FL)

    Clarity Grading with a 10x Loupe

    • Clarity is primarily graded from the table view when using a 10x loupe

    Non-Lab Testing

    • Observations used to determine the ID of a stone in non-lab testing include thermal conductivity, electrical conductivity, and optical properties
    • The Thermal conductance probe and Electrical conductance probe are used to conduct tests in non-lab testing
    • A Polariscope aids in the testing of diamonds by detecting birefringence and strain patterns
    • The Tatami strain pattern indicates a diamond when viewed using a Polariscope

    Identifying Synthetic Diamonds

    • Crossed polarizing filters can help in identifying synthetic diamonds by detecting their birefringence
    • Plastic deformation in diamonds viewed under crossed polars indicates a natural diamond
    • Metallic inclusions are observed in HPHT synthetic diamonds
    • Clarity treatments involving fracture filling are observed in some diamonds

    Laser Inscriptions and Detection

    • Laser inscriptions can be identified on diamonds
    • The DTC DiamondSure Portable is used to detect diamond authenticity
    • The DTC DiamondView determines natural or synthetic diamonds by detecting their optical and spectroscopic properties

    Synthetic Diamond Identification

    • Distinctive growth patterns are observed in HPHT synthetic diamonds
    • Diamonds can be detected based on their growth patterns and fluorescence
    • The basis for identifying diamond types using specialized screening equipment is their optical and spectroscopic properties
    • The Cathodoluminescence (CL) test assesses the presence of defects in diamonds

    Synthetic Moissanite Detection

    • The presence of synthetic moissanite can be detected using the DTC DiamondSure Portable

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    Test your knowledge about assessing the value of a cut diamond according to the four factors known as the 'four C’s': Carat Weight, Colour, Clarity, and Cut quality. Explore how these factors contribute to the overall value of a diamond.

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