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29 Cards in this Set
- Front
- Back
Define 'cleavage'.
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A smooth, flat break in a gemstone parallel to planes of atomic weakness.
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Define 'conchoidal fracture'.
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A curved and ridged fracture in a gemstone, extending from the surface inward.
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Define 'dispersion'.
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The separation of white light into spectral hues.
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Define 'fire'.
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The flashes of spectral color you see in a polished gem, especially a diamond.
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Define 'fracture'.
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Any break in a gem other than cleavage or parting.
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Define 'granular fracture'.
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A sugary or grainy fracture that appears in microcrystalline aggregates.
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Define 'heft'.
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The weight or heaviness of an object compared to its size.
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Define 'luster'.
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The appearance of a material's surface in reflected light.
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Define 'opaque'.
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Description of a material that's unable to transmit lihgt, so an image can't be seen through it.
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Define 'parting'.
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A flat break in a gemstone parallel to a twinning plane.
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Define 'splintery fracture'.
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A gemstone fracture that looks like broken wood, resulting from the fibrous structure of certain gems.
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Define 'translucent'.
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Description of a material that's capable of partially transmitting light so an image seen through it appears obscure, with a vague outline.
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Define 'transparency'.
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The degree to which a material transmits light.
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Define 'transparent'.
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Description of a material that's capable of transmitting light so objects viewed through it appear clear and sharp.
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What is the transparency of a material that only partially transmits light so that an image seen through it has just a vague outline?
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Translucent.
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What is asterism caused by?
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Reflections from precisely oriented, needle-like inclusions.
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What are the 3 things that a material's luster is dependent on?
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RI
Hardness Quality of its polish |
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What is a smooth break parallel to a gem's twinning plane called?
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Parting.
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What is the first test when starting the Gem ID process?
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General observation.
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What is another name for the 'Cats-eye' effect?
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Chatoyancy.
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What is the most common luster for transparent gems?
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Vitreous.
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What have you got if you observe a red ring during the examination of a gem?
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A garnet-and-glass doublet.
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How do you record a very light violetish blue bodycolor on a Gem ID worksheet?
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vlvB.
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What would you record a gem's cutting style as if it had a design engraved into its surface?
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Intaglio.
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What is a curved, ridged fracture extending inward from the surface of a gem called?
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Conchoidal.
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What might a colorless gem be if you observe extreme fire?
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Synthetic Rutile.
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When can heft NOT be tested?
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When a gem is mounted.
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What is another term for an unusual optical effect?
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Phenomenon.
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What is the degree to which a material transmits light called?
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Transparency.
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