Quality Assurance & Control Flashcards

What is the best routine check that a gemological refractometer is reading accurately?

Answer: Test a known quartz specimen and confirm readings of about 1.544–1.553

Quartz has well-known, stable RIs within the refractometer's range, so it is an ideal reference stone.

Which lighting condition is standard for consistent diamond color grading?

Answer: Daylight-equivalent fluorescent light of about 6500K in a neutral environment

Controlled daylight-equivalent light near 6500K keeps color grading consistent and repeatable.

What is the main quality-control purpose of a diamond master stone set?

Answer: To provide fixed physical references so color grades stay consistent

Master stones of known color grade are reference points that reduce grader drift.

How should the accuracy of a jeweler's carat balance be verified?

Answer: Weigh calibrated reference weights traceable to a national standard

Certified reference weights traceable to standards such as NIST give an objective accuracy check.

Which magnifier is the industry standard for clarity grading?

Answer: A fully corrected 10x triplet loupe

Clarity grades are defined by what is visible under 10x magnification, and a corrected triplet minimizes distortion.

Under the FTC Jewelry Guides, how accurate must a decimal carat weight statement be?

Answer: Accurate to the last decimal place stated

The FTC Guides say a decimal weight representation must be accurate to the last decimal figure given.

Before testing a stone, what should a consultant confirm on a polariscope?

Answer: The polarizers are crossed so the field is dark

Correct readings need crossed polarizers, which give a dark field.