Mixed Deck — All CDG Topics Flashcards

A diamond tests positive on a standard thermal conductivity tester but displays unusual strain patterns under the microscope. What is the correct risk management response?

Answer: Submit the stone for advanced spectroscopic or photoluminescence testing

Standard testers confirm thermal conductivity but cannot distinguish all synthetics or certain simulants; conflicting evidence requires escalation to definitive spectroscopic analysis.

How does KM (Kiduah Meyuchad) drilling differ from traditional laser drilling?

Answer: It creates a surface-reaching fracture rather than a straight drill hole

KM drilling creates a surface-reaching fracture that reaches the inclusion without leaving a straight drill hole, making it harder to detect than traditional laser drilling.

What substance is most commonly used in fracture filling of diamonds?

Answer: Lead glass (high lead-content glass)

Lead glass is the most common fracture-filling material because its refractive index closely matches that of diamond, making the filled fractures nearly invisible.

Which method is commonly used for root cause analysis in CDG quality management?

Answer: The Five Whys technique or fishbone diagram for systematic investigation

Structured root cause analysis methods like Five Whys and fishbone diagrams systematically trace problems to their fundamental causes rather than symptoms.

What is the role of internal audits in Certified Diamond Grader compliance management?

Answer: They verify adherence to regulations and identify areas needing improvement

Internal audits proactively verify compliance, identify gaps, and drive improvement before external inspections or incidents reveal problems.

The difference between a diamond grading report and a diamond appraisal is best described as:

Answer: A grading report documents gemological properties; an appraisal assigns monetary value

Grading reports objectively document the 4Cs and other properties, while appraisals assign a monetary value for insurance or resale purposes.

Which risk is most critical when grading a diamond submitted alongside a GIA grading report?

Answer: Assuming the report is authentic without verification

Report fraud exists, so cross-referencing the laser inscription and physical characteristics against the document is essential before relying on it.

How should an CDG professional present complex findings to non-experts?

Answer: Translate into accessible language, use visuals, and verify understanding

Complex information should be translated into accessible language with visual aids, followed by checking for understanding to ensure effective communication.

A diamond has 65 facets instead of the standard 58 due to extra facets on the pavilion. How do extra facets affect the GIA cut grade?

Answer: Extra facets are noted as a symmetry characteristic and can lower the symmetry grade if they are asymmetrical

Extra facets are a symmetry characteristic; if they are asymmetrically placed or visually disruptive, they are noted on the report and may lower the symmetry grade.

What does the Kimberley Process aim to prevent?

Answer: Conflict diamond trade

The Kimberley Process Certification Scheme (KPCS) is an international agreement designed to prevent the trade of conflict diamonds. Conflict diamonds are rough diamonds used by rebel movements to finance wars against legitimate governments. The KPCS aims to ensure that diamonds are sourced ethically and do not contribute to armed conflict, thereby promoting peace and human rights.

What is the Mohs scale used to measure?

Answer: Hardness

The Mohs scale of mineral hardness is a qualitative ordinal scale that measures the scratch resistance of various minerals. It ranks minerals from 1 (softest, like talc) to 10 (hardest, like diamond) based on their ability to scratch or be scratched by other minerals. This scale is a crucial tool for mineral identification and determining a gemstone's durability.

Why is market knowledge important for diamond graders?

Answer: To provide accurate valuations

Market knowledge is crucial for diamond graders because it allows them to understand current demand, supply, and pricing trends for different diamond qualities. This understanding, combined with their grading expertise, enables them to provide more accurate and relevant valuations. Without market context, a grading report alone cannot fully determine a diamond's fair market value.

What distinguishes a 'lamination' inclusion in a diamond?

Answer: A flat, reflective platelet parallel to crystal planes

Laminations are flat, reflective inclusions (often nitrogen platelets) that lie parallel to the octahedral crystal planes within a diamond.

What property refers to how light bends inside a mineral?

Answer: Refraction

Refraction is the phenomenon where light bends as it passes from one medium into another, such as from air into a mineral. This bending occurs because light changes speed when entering a material with a different optical density. A mineral's refractive index, which quantifies this bending, is a key optical property used in gem identification and understanding a gemstone's brilliance.

A diamond showing a 415 nm absorption line in its UV-Vis spectrum is most likely:

Answer: A Cape series (Type Ia) light yellow diamond

The 415 nm line (N3 center) is the diagnostic feature of Cape series diamonds, which are Type Ia stones with a light yellow to yellow body color.

Which clarity characteristic type CANNOT be improved through laser drilling?

Answer: White feathers or clouds

Laser drilling targets high-contrast dark inclusions, so white feathers or clouds — which are already low-contrast — offer no benefit from the procedure.

You are grading a round brilliant with a girdle that grades as Thick to Very Thick. What is the most significant concern this raises beyond the girdle grade itself?

Answer: The extra weight in the girdle increases carat weight without contributing to face-up size, reducing value per carat

A very thick girdle hides excess weight that does not contribute to face-up diameter, meaning the stone appears smaller than its carat weight would suggest, reducing value per carat.

How should an CDG professional handle unexpected results that differ from predictions?

Answer: Analyze factors, document findings, and adjust the approach based on what was learned

Unexpected results are learning opportunities. Professional practice requires analysis of contributing factors and adaptation based on those findings.

When handling a diamond worth over $100,000 in a professional laboratory, security protocol typically requires:

Answer: Enhanced chain of custody documentation and dual verification at each transfer point

High-value stones require enhanced documentation and dual verification at each transfer to minimize risk and maintain accountability.

A professional diamond grader should recuse themselves from grading a stone when:

Answer: They have a financial interest in the stone's grade outcome

A financial interest in the grading outcome creates an irreconcilable conflict of interest that requires recusal to protect objectivity.