DCA QUESTIONS AND SOLUTIONS 2025/2026 GRADED A+
✔✔colorless sapphire, quartz, and colorless zircon - ✔✔Natural gemstones that are
used as diamond simulants
✔✔synthetic spinel, sapphire, and glass - ✔✔The most common simulants in terms of
volume
✔✔flash effect, color zoning, and unusual florescene equates w/ synthetic diamond -
✔✔Tests that can be used to separate diamonds from simulants, or to identify treatment
of synthetic diamonds
✔✔thermal reaction testers separate diamonds from simulants except moissanite -
✔✔The products that can be identified with the instruments and test available in many
jewelry stores
✔✔a flat, triangular crystal resulting from twinning - ✔✔Macle
✔✔the potential to break in crystal directions - ✔✔Cleavage (property)
✔✔resistance to scratching 1-10, 10=hardest - ✔✔Mohs Hardness Scale
✔✔8 sided; resembles 2 pyramids joined - ✔✔Octahedron
✔✔most common crystal form for gem quality diamonds - ✔✔Crystal habit
✔✔combo. of chemical composition and crystal structure produces diamonds inherent
characteristics - ✔✔Property
✔✔box-like w/ 6 square sides - ✔✔Cube
✔✔slowing and bending of light - ✔✔Refraction
✔✔relationship between size and weight - ✔✔Density
✔✔compares the speed of light in air to its speed in the material - ✔✔Refractive index
(RI)
✔✔under the rock platforms, called cratons, which form the cores of continents -
✔✔Diamond stability field
✔✔weight of material vs. the weight of an = volume of water - ✔✔Specific gravity (SG)
, ✔✔12 sided, rounded form, has flattend and elongated crystals, and makes brilliants -
✔✔Dodecahedron
✔✔resistance to breaking - ✔✔Toughness
✔✔resistance to scratching - ✔✔Hardness
✔✔octahedron - ✔✔The most common crystal form for gem diamonds
✔✔SG=3.52 , RI=2.417, dispersion=0.044 - ✔✔The specific gravity, refractive index,
and dispersion of diamond
✔✔main body of the pipe that contains majority of diamonds - ✔✔Diatreme
✔✔carrot-shaped pipes, carried most diamonds - ✔✔Kimberlite
✔✔largest single delivery found-Argyle deposit in Australia - ✔✔Lamproite
✔✔diamonds carried by erosion - ✔✔Secondary deposit
✔✔via kimberlite and lamproite - ✔✔How primary and secondary diamond deposits
were formed
✔✔secondary deposits yield higher percentages of gem quality diamonds - ✔✔How
production from primary deposits compares with that of secondary deposits
✔✔4 billion carats and 130 million carats - ✔✔The estimated total of diamond
production for all of history, and current annual production
✔✔Arkansas, Colorado, Michigan, and Wyoming - ✔✔The US states with diamond
deposits or mines
✔✔number of carats per ton of ore - ✔✔Grade
✔✔spots diamonds in secondary deposits, like garnet, spinel, and zircon - ✔✔Indicator
mineral
✔✔a gigantic spiral hole, most commonly used for mining - ✔✔Open pit mining
✔✔barren rock - ✔✔Overburden
✔✔ore processing: ore 1st goes via crushers, screens, scrubber, then separator -
✔✔Recovery
✔✔colorless sapphire, quartz, and colorless zircon - ✔✔Natural gemstones that are
used as diamond simulants
✔✔synthetic spinel, sapphire, and glass - ✔✔The most common simulants in terms of
volume
✔✔flash effect, color zoning, and unusual florescene equates w/ synthetic diamond -
✔✔Tests that can be used to separate diamonds from simulants, or to identify treatment
of synthetic diamonds
✔✔thermal reaction testers separate diamonds from simulants except moissanite -
✔✔The products that can be identified with the instruments and test available in many
jewelry stores
✔✔a flat, triangular crystal resulting from twinning - ✔✔Macle
✔✔the potential to break in crystal directions - ✔✔Cleavage (property)
✔✔resistance to scratching 1-10, 10=hardest - ✔✔Mohs Hardness Scale
✔✔8 sided; resembles 2 pyramids joined - ✔✔Octahedron
✔✔most common crystal form for gem quality diamonds - ✔✔Crystal habit
✔✔combo. of chemical composition and crystal structure produces diamonds inherent
characteristics - ✔✔Property
✔✔box-like w/ 6 square sides - ✔✔Cube
✔✔slowing and bending of light - ✔✔Refraction
✔✔relationship between size and weight - ✔✔Density
✔✔compares the speed of light in air to its speed in the material - ✔✔Refractive index
(RI)
✔✔under the rock platforms, called cratons, which form the cores of continents -
✔✔Diamond stability field
✔✔weight of material vs. the weight of an = volume of water - ✔✔Specific gravity (SG)
, ✔✔12 sided, rounded form, has flattend and elongated crystals, and makes brilliants -
✔✔Dodecahedron
✔✔resistance to breaking - ✔✔Toughness
✔✔resistance to scratching - ✔✔Hardness
✔✔octahedron - ✔✔The most common crystal form for gem diamonds
✔✔SG=3.52 , RI=2.417, dispersion=0.044 - ✔✔The specific gravity, refractive index,
and dispersion of diamond
✔✔main body of the pipe that contains majority of diamonds - ✔✔Diatreme
✔✔carrot-shaped pipes, carried most diamonds - ✔✔Kimberlite
✔✔largest single delivery found-Argyle deposit in Australia - ✔✔Lamproite
✔✔diamonds carried by erosion - ✔✔Secondary deposit
✔✔via kimberlite and lamproite - ✔✔How primary and secondary diamond deposits
were formed
✔✔secondary deposits yield higher percentages of gem quality diamonds - ✔✔How
production from primary deposits compares with that of secondary deposits
✔✔4 billion carats and 130 million carats - ✔✔The estimated total of diamond
production for all of history, and current annual production
✔✔Arkansas, Colorado, Michigan, and Wyoming - ✔✔The US states with diamond
deposits or mines
✔✔number of carats per ton of ore - ✔✔Grade
✔✔spots diamonds in secondary deposits, like garnet, spinel, and zircon - ✔✔Indicator
mineral
✔✔a gigantic spiral hole, most commonly used for mining - ✔✔Open pit mining
✔✔barren rock - ✔✔Overburden
✔✔ore processing: ore 1st goes via crushers, screens, scrubber, then separator -
✔✔Recovery
