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State PCS PYQPrelims 2023

BPSC – Combined Competitive Examination · Question 10

In the context of lab-grown diamonds (LGDs), what is used as the starting carbon material ('seed')?

  1. White sapphire
  2. Moissanite
  3. Graphite
  4. Cubic zirconia (CZ)
Show answer & explanation

Answer: (C) Graphite

Explanation

Lab-grown diamonds must start from carbon; in the HPHT method graphite is the carbon source (CVD uses a thin diamond seed plate with methane).

  • (A) Incorrect

    Wrong: aluminium oxide; contains no carbon.

  • (B) Incorrect

    Wrong: silicon carbide; a diamond simulant.

  • (C) Correct

    Correct: graphite, a form of carbon, is converted to diamond under high pressure and temperature.

  • (D) Incorrect

    Wrong: zirconium dioxide; a diamond simulant.