GIA Laboratory Testing & Equipment 2

Question 1

Which instrument uses a diffraction grating to separate light into its spectral components for diamond testing?

Accepted Answer

Spectroscope

Answer

A spectroscope separates light using a diffraction grating or prism to reveal absorption lines that help identify gemstones.

Question 2

When using a thermal conductivity probe on a diamond, what does a high reading indicate?

Accepted Answer

The stone is a genuine diamond or moissanite

Answer

Diamonds and moissanite both conduct heat rapidly, causing a high thermal conductivity reading, so a secondary test is needed to distinguish them.

Question 3

What is the primary function of a Chelsea color filter when examining diamonds?

Accepted Answer

Separate colored stones from colorless diamonds

Answer

The Chelsea filter transmits red and yellow-green light, helping distinguish certain colored stones, though it has limited use with colorless diamonds.

Question 4

In spectroscopy, the Cape series absorption lines in natural diamonds appear at which wavelength range?

Accepted Answer

415–478 nm

Answer

Cape series diamonds show a characteristic absorption line at 415 nm (and sometimes 452 nm and 478 nm) due to nitrogen aggregates.

Question 5

Which type of microscope stage is most useful when examining a diamond for strain patterns?

Accepted Answer

Polarized light stage

Answer

A polarized light stage reveals anomalous birefringence and strain patterns that can help identify certain diamond treatments or synthetic origins.

(GIA) Certified Diamonds Gemological Institute of America Practice Test

(GIA) Certified Diamonds Gemological Institute of America Practice Test

GIA Laboratory Testing & Equipment 2