Ass #12 - Key Terms and Concepts

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Questions and Answers

What is the Average Girdle Diameter of a diamond?

The angle formed by the bezel facets and the girdle plane.

The sum of the smallest and largest diameter measurements divided by two. (correct)

The width of a diamond's girdle measured in millimeters.

The result of dividing the smallest diameter measurement by the largest diameter measurement.

What does the Crown Height Percentage represent?

The thickness of the girdle in relation to the overall size of the diamond.

The distance from the girdle plane to the table expressed as a percentage of average girdle diameter. (correct)

The total depth of a diamond measured from the table to the culet.

The size of the table facet expressed as a percentage of the diamond's depth.

What common issue can arise from severe painting and digging out during diamond cutting?

It enhances the diamond's clarity characteristics.

It increases the weight of the diamond significantly.

It results in a more pronounced crown angle.

It can cause uneven scalloping around the girdle and hill positions of differing thicknesses (correct)

Which of the following best describes Table Percentage?

A diamond's table size expressed as a percentage of its average girdle diameter. Signup and view all the answers

What is the effect of a shallow crown on diamond cutting?

It may save weight but can negatively affect appearance. Signup and view all the answers

What is the primary purpose of the Table Gauge in diamond measurement?

To measure a diamond’s table in millimeters and tenths of a millimeter. Signup and view all the answers

Which of the following is a potential consequence of excessive digging out or painting in a diamond?

An unattractive scintillation pattern or make it appear darker. Signup and view all the answers

What is the purpose of measuring a diamond’s table size in four directions?

To ensure accurate average measurements. Signup and view all the answers

What should be a consideration when evaluating the girdle thickness of a diamond?

It should be thick enough to prevent chipping without detracting from appearance. Signup and view all the answers

What does Star Length Percentage indicate?

The length of star facets as a percentage of the total distance from girdle to table edge. Signup and view all the answers

The angle formed by the bezel facets and the girdle plane .....

Crown Angle Signup and view all the answers

Diamonds are always measured in .........

Millimeters Signup and view all the answers

Table-to-culet depth, expressed as a percentage of average girdle diameter is defined as the ......

Total Depth Percentage Signup and view all the answers

The width of a fashioned gem’s girdle is .....

girdle thickness Signup and view all the answers

Cutting technique that thins the area of the girdle where the upper half facet junctions meet the lower half facet junctions, to retain weight or remove clarity characteristics.

Digging Out Signup and view all the answers

Cutting technique that thins the area of the girdle where the bezel and pavilion main meet, to retain weight or remove clarity characteristics.

Painting Signup and view all the answers

What is the basis for comparing a diamond’s other proportions?

Average girdle diameter Signup and view all the answers

Table size estimation techniques can be.......

be quick and fairly accurate. Signup and view all the answers

Most round brilliants have table percentages that range from......

about 55 percent to about 65 percent. Signup and view all the answers

Study Notes

DDG Ass #12 Key Terms

Average Girdle Diameter: Result of adding smallest and largest diameter measurements, then dividing by two.
Crown Angle: Angle between bezel facets and girdle plane.
Crown Height Percentage: Distance from girdle to table, expressed as a percentage of average girdle diameter.
Digging Out: Cutting technique thinning girdle area where upper and lower half facet junctions meet; used to retain weight or remove clarity.
Girdle Thickness: Width of a fashioned gem's girdle.
Painting: Cutting technique thinning girdle area where bezel and pavilion meet; used to retain weight or remove clarity.
Star Length Percentage: Length of star facets, expressed as a percentage of the total distance from girdle to table edge.
Table Gauge: Transparent measuring device used to measure diamond table in millimeters and tenths.
Table Percentage: Diamond's table size, expressed as a percentage of average girdle diameter.
Total Depth Percentage: Table-to-culet depth, expressed as a percentage of average girdle diameter.

Key Concepts

Average Girdle Diameter: Basis for comparing diamond proportions.
Diamond Table Percentage: Most round brilliants range from 55% to 65%
Diamond Measurement: Diamonds are measured in millimeters.
Table Size Determination: Measure table facet in four directions; average measurements to determine table size.
Table Estimation Techniques: Techniques can be quick and fairly accurate with practice.
Shallow Crown: Can help save weight from rough, but may negatively affect appearance.
Girdle Thickness: Should be thick enough to prevent chipping, but not so thick it detracts from appearance.
Painting & Digging Out: Severe painting/digging out results in uneven thickness/scalloping around the girdle, creating unattractive scintillation patterns, or making the diamond appear darker.

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Description

Test your knowledge of essential gemology terms with this quiz. You'll encounter key concepts related to diamond cutting, measurements, and techniques. Perfect for students and professionals in the field of gemology.