Ass #15 - Estimating Weight, Recutting

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Questions and Answers

What should be checked to assess the girdle's thickness and condition in a bezel setting?

Observe the prongs’ alignment.

Check its reflection in the pavilion. (correct)

Inspect the girdle’s color and clarity.

Measure the distance from the table to the culet.

How can total depth percentage be determined for a mounted stone?

By calculating the average between the upper and lower facets.

By measuring from the table to the girdle.

By getting the measuring device to contact the diamond’s culet. (correct)

By estimating based on the stone's girdle thickness.

Which factor has the greatest effect on estimated weight of a diamond?

Culet size.

Crown height percentage.

Girdle thickness. (correct)

Pavilion depth percentage.

What must be assessed to judge pavilion depths and angles in mounted stones?

The stone’s profile if the mounting allows it. Signup and view all the answers

What adjustment is made for estimating the weight of diamonds with a thick girdle?

Use the Weight Correction Factors for Thicker Girdles chart. Signup and view all the answers

What is the primary goal of repolishing a diamond?

To restore or improve its appearance Signup and view all the answers

Which grade can a diamond considered a 'potential' achieve after repolishing?

Internally Flawless (IF) Signup and view all the answers

What factor is NOT considered when determining the value increase from clarity-improving repolishing?

Diamond's cut shape Signup and view all the answers

In the context of diamond recutting, what is the main purpose of adding extra facets?

To increase sparkle and light reflection Signup and view all the answers

Which of the following processes does NOT involve altering the weight of a diamond?

Repolishing Signup and view all the answers

What is important to determine when estimating the weight of a round brilliant diamond?

Average diameter and depth in millimeters Signup and view all the answers

When estimating the weight of fancy cut diamonds, what dimensions are essential?

Length and width Signup and view all the answers

What adjustment factor is used for in diamond weight estimation formulas?

Length-to-width ratio Signup and view all the answers

Which method is likely to improve the visibility of a diamond's clarity while mounted?

Using a fiber-optic lighting system Signup and view all the answers

What is the primary reason a diamond owner typically prioritizes weight over beauty when considering recutting?

The value of the diamond is impacted by its weight. Signup and view all the answers

What is the primary reason a mounting can affect the assessment of a diamond's clarity?

Mountings can hide blemishes and inclusions Signup and view all the answers

Which recutting technique is typically less expensive for improving diamond clarity?

Laser drilling and bleaching. Signup and view all the answers

What grading approach is typically used for small mounted diamonds?

A range of two possible grades Signup and view all the answers

What is a significant risk associated with attempting to improve a diamond’s color through recutting?

Sacrificing up to 25% of the diamond’s weight. Signup and view all the answers

Which observation method is effective for evaluating a diamond's color when it is in a solitaire setting?

Holding the diamond table-down while comparing with masterstones Signup and view all the answers

When estimating a mounted diamond's diameter, which part of the setting may obstruct accurate measurement?

The girdle edge Signup and view all the answers

What type of diamonds can typically be recut into modern brilliants without considerable loss in diameter?

Diamonds with high crowns and deep pavilions. Signup and view all the answers

For large mounted diamonds, how is the color grade typically assigned?

A single grade Signup and view all the answers

How does the original cut influence the recutting style of a diamond?

It dictates the style options available for recutting. Signup and view all the answers

Which recutting approach is commonly used to modernize diamonds with older cutting styles?

Creating custom cuts from rough stones. Signup and view all the answers

What technique might help in viewing the area under a prong while grading a diamond's clarity?

Finding the prong's reflection and examining the surrounding area Signup and view all the answers

What common feature do all diamonds that are ideal for recutting into modern brilliants share?

They have distinctive crown and pavilion characteristics. Signup and view all the answers

What is a challenge faced when estimating the crown angle of a mounted diamond?

It is easier to estimate with the face-up method Signup and view all the answers

What factor is often evaluated when deciding whether to recut a diamond?

The potential future appearance and value. Signup and view all the answers

What impact does the metal of a mounting have on a diamond's appearance?

It can influence the diamond's apparent color Signup and view all the answers

Which method is NOT recommended for measuring a mounted diamond's dimensions?

Taking measurements from a previous appraisal Signup and view all the answers

What is the most common purpose for recutting diamonds?

To enhance their brightness and fire balance. Signup and view all the answers

What is one disadvantage of recutting a diamond with shallow crown and pavilions?

It can lead to considerable weight loss. Signup and view all the answers

Study Notes

Grading Mounted Diamonds

Mounting a diamond makes assessing its characteristics difficult, as it hides parts of the stone.
Fiber-optic lighting systems aid in prong inspection by reflecting light.
Clarity grades for large diamonds are often presented as a singular grade, while small diamonds may have a range of two grades.
Color evaluation uses a method for D-to-Z color range diamonds. One approach involves holding the diamond in a table-down position, moving along masterstones. Another involves holding both the mounted stone and masterstone side-by-side for face-up comparisons.
Metal can impact a diamond's apparent color.
Determining dimensions with a millimeter gauge is possible if the mounting allows access to the girdle. Estimating girdle dimensions is necessary when parts are covered.
Crown angle estimation is often easier with a face-up method, using table percentage and crown angle charts.
Girdle thickness is assessed by observing visible areas & those hidden by prongs.
Pavilion depth estimations work the same for loose and mounted stones, by using reflections to evaluate hidden areas.
Total depth percentages are determined by subtracting crown height & pavilion depth percentages

Estimating Diamond Weight

Professionals use formulas to calculate mounted diamond weights—these formulas consider proportions.
Accurate weight estimation relies on experience with practice.
Girdle thickness significantly affects estimated weight.
Weight correction charts apply to round and fancy-shape diamonds with thicker girdles.
Diamond shapes (including fancy cuts) need weight corrections, which range from 1%-12% affecting the estimations. Specific factors include differences in pavilion bulge, high shoulders, or bulged wings of the diamond's facets.
For round brilliants, weight estimation is dependent on the average diameter, depth, and overall girdle thickness.
Calculating weight for fancy cuts uses length, width, and length to width ratio calculations to estimate via formulas.
Clustered diamond weight estimation is obtained by measuring each stone, categorizing by size, and summing the category totals.

Repolishing and Recutting

Repolishing involves refinishing to resolve clarity and finish issues.
Some diamonds may benefit from additional facets to correct imperfections.
Repolishing may improve a diamond's clarity grade.
Repolishing or faceting the girdle can smooth the surface and potentially affect the diamond's color.
Full recutting involves resetting a diamond to improve clarity, proportions, or color—or to update older styles.
Recuts aim to compromise weight and aesthetics due to cost.
Recutting might involve adjusting brightness, fire balance , or potentially color by recutting to improve color.
Recutting may be used to address inclusion/clarity issues, in which laser drilling or bleaching techniques are options.
Diamonds are sometimes recut to update old cutting styles

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Description

This quiz explores the techniques and challenges involved in grading diamonds that are mounted. It covers methods for assessing clarity, color, and dimensions, while also discussing the impact of mounting on evaluation. Test your knowledge on the precision required in diamond grading.