Gemology & Mineralogy Fundamentals Flashcards

Which spectroscopic method is considered the gold standard for diamond type classification?

Answer: Infrared (IR) spectroscopy

Infrared spectroscopy reveals nitrogen aggregation patterns, boron content, and hydrogen features that define diamond types (Ia, Ib, IIa, IIb).

A diamond showing a 415 nm absorption line in its UV-Vis spectrum is most likely:

Answer: A Cape series (Type Ia) light yellow diamond

The 415 nm line (N3 center) is the diagnostic feature of Cape series diamonds, which are Type Ia stones with a light yellow to yellow body color.

The phrase 'point of equal angles' in gemology refers to:

Answer: The principle that the angle of incidence equals the angle of reflection

The law of reflection states that the angle of incidence equals the angle of reflection, a fundamental optical principle governing how light behaves inside a cut gem.

Which of the following best describes the mineral 'moissanite' in relation to diamond?

Answer: A diamond simulant composed of silicon carbide (SiC)

Moissanite (SiC) is a popular diamond simulant because its properties closely mimic diamond, though it is doubly refractive and has a different thermal conductivity profile.

What does the term 'parting' mean in mineralogy as it applies to gem identification?

Answer: Breakage along planes of weakness due to twinning or structural irregularities

Parting occurs along planes weakened by twinning, pressure, or structural defects, producing flat breaks that resemble cleavage but are not true cleavage.

Which naturally occurring mineral is the closest in hardness to diamond on the Mohs scale?

Answer: Corundum/ruby/sapphire (Mohs 9)

Corundum (ruby and sapphire) rates 9 on the Mohs scale, one step below diamond at 10; however, diamond is actually several times harder in absolute terms.

In diamond mineralogy, 'fibrous' rough diamond growth refers to:

Answer: Rapid, turbulent crystallization producing a cloudy, fibrous internal texture

Fibrous diamonds result from rapid crystallization in a volatile-rich environment, trapping minute fluid inclusions and producing a cloudy or milky appearance.