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29 Cards in this Set

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