Ass #15 - Estimating Weight, Recutting

Estimating the weight of a round brilliant diamond requires knowing its diameter, depth, and girdle thickness in millimeters.

Measure the diameter of the girdle at multiple points between the prongs to determine the average diameter for weight calculations.

Estimating the weight of fancy-cut diamonds requires knowing the length and width of the stone.

Repolishing corrects minor clarity or finish flaws in a diamond by refinishing or adding facets.

Repolishing can improve a diamond's clarity grade, potentially increasing its value.

To find the total weight of a cluster of small diamonds (like baguettes or rounds), measure each stone, group by size, and sum the weights of each size category.

Repolishing aims to restore or improve the appearance of a diamond.

Polishing/faceting the girdle can remove imperfections creating a smoother surface, sometimes improving color.

Repolishing a diamond to improve its clarity, proportions, color, or style.

Removing inclusions from a diamond by cutting it

Changing a diamond's color by altering its cut.

Updating an old diamond cut to a newer style.

Trade-off between keeping the weight of a diamond and improving its look

Modern diamond cuts that are popular today.

Older diamond cuts, such as old European and old mine cuts

Four categories of diamonds recut effectively into modern brilliants based on crown & pavilion depths.

Diamond cuts with tall tops and deep bottoms. Generally favorable when recutting.

Diamond cuts that can yield high weight losses when recutting.

It's impossible to accurately weigh a diamond when it's mounted. The setting obscures the stone's true weight.

Evaluating a mounted diamond's clarity is tricky. Prongs hide flaws, and the lighting can distort the view.

Use a fiber-optic light system to illuminate the hidden areas under prongs. For higher clarity diamonds, the stone might need to be removed.

The setting's metal can influence the diamond's apparent color. Color is best evaluated using a table-down or side-by-side comparison with a masterstone.

Estimating a mounted diamond's dimensions is challenging. You might need to measure the stone's diameter and estimate the girdle location.

Estimating a mounted diamond's crown angle is easier with the face-up method than the profile method.

Appraisers typically give a single clarity grade for large diamonds and a range of two possible grades for smaller mounted diamonds.

Large, mounted diamonds get a single color grade, while smaller mounted diamonds typically get a range of two possible color grades.

Polishing the girdle can remove imperfections, create a smoother surface, and sometimes improve the diamond's color.

The percentage of the diamond's total depth that is occupied by the crown, important for understanding the diamond's proportions and appearance.

The thickness of the diamond's girdle, which is the ring-like edge separating the crown and pavilion, contributes significantly to the diamond's weight.

The percentage of the diamond's total depth that is occupied by the pavilion, the bottom part of the diamond, that reflects light back to the eye.

Adjustments to the weight estimate of diamonds based on their girdle thickness and other shape variations.

Estimating the weight of fancy-cut diamonds involves considering the length and width, but also the girdle thickness and shape variations.