CBJ Core Knowledge and Fundamentals 5

Question 1

What is the function of flux when soldering precious metals?

Accepted Answer

It prevents oxidation and promotes solder flow

Answer

Flux prevents metal oxides from forming during heating and helps solder wet and flow along clean metal surfaces by reducing surface tension.

Question 2

A platinum ring must be repaired adjacent to a pave-set diamond melee. What is the safest approach?

Accepted Answer

Use a laser welder to minimize heat spread to the stones

Answer

A laser welder delivers highly localized heat with minimal thermal spread, making it the safest tool for repairs close to set stones.

Question 3

What does 'karat' measure in gold jewelry?

Accepted Answer

The proportion of pure gold in an alloy, out of 24 parts

Answer

Karat measures gold purity as a fraction of 24 — 24 karat is pure gold, 18 karat is 18/24 (75%) gold, and 14 karat is 14/24 (58.3%) gold.

Question 4

Which hand file shape is most useful for cleaning up the inside of a ring shank after sizing?

Accepted Answer

Round file

Answer

A round (rat-tail) file fits inside the curved interior of a ring shank and can smooth solder seams and rough areas on the inner surface.

Question 5

What is the specific gravity of fine gold (24K)?

Accepted Answer

19.3

Answer

Fine gold has a specific gravity of approximately 19.3, meaning it is 19.3 times denser than an equal volume of water.

(CBJ) Certified Bench Jeweler Practice Test