Which of the following seed is used in production of engineered diamonds?

Correct answer: (c) Graphite

Explanation

Graphite is the seed/source material for engineered (synthetic) diamonds, as both are forms of pure carbon.

In the HPHT (High Pressure High Temperature) method, graphite is converted into diamond; CVD is the other common process.

Moissanite, white sapphire and cubic zirconia are diamond simulants, not carbon sources.