Ass #9 - Clarity vs Blemishes

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Questions and Answers

Which characteristic is specifically referred to as a dop burn?

A small dot that results from pinpoint inclusions

A haze caused by excessive heat during polishing

A surface burn due to excessive heat at the contact point of the dop (correct)

Burn marks caused by a jeweler’s torch

What is the primary cause of lizard skin on a polished diamond?

Excessive heat from the polishing process

Rubbing against another diamond during cutting

Polishing too closely to the octahedral plane (correct)

Inclusion marks that break the surface

Which type of mark might occur during polishing that resembles an extra facet?

Pit

Scratch

Polish mark (correct)

Polish line

Which term describes the surface irregularity similar to the surface of a sugar cube?

Rough girdle Signup and view all the answers

What is the outcome when pinpoint inclusions are removed during the polishing process?

Pit Signup and view all the answers

What is an extra facet primarily used for in diamond cutting?

To determine polishing directions Signup and view all the answers

Which characteristic is specifically created during a laser manufacturing process?

Laser manufacturing remnant Signup and view all the answers

Which defect is caused by excessive heat during polishing?

Burn Signup and view all the answers

What does a scratch on a diamond primarily appear as?

A dull white line Signup and view all the answers

What feature shows growth marks and remains from the original diamond surface?

Natural Signup and view all the answers

Which term refers to any break in a diamond?

Feather Signup and view all the answers

What appearance does a heavily bearded girdle have?

A fuzzy gray fringe all around the diamond Signup and view all the answers

How is cleavage defined in the context of diamonds?

A break that occurs at a cleavage plane Signup and view all the answers

What type of inclusion consists of tight clusters of pinpoints that can affect a diamond's transparency?

Cloud Signup and view all the answers

What can the appearance of internal graining resemble?

Lines or angles Signup and view all the answers

Which feature is defined as appearing flat and ribbon-like, radiating from the diamond's center?

Twinning wisp Signup and view all the answers

What aspect does internal graining that appears colorless or transparent not affect?

The clarity grade Signup and view all the answers

What is an etch channel?

An angular opening that extends into a diamond Signup and view all the answers

Which term is used for a small concentrated area of crystal growth distortion within a diamond?

Grain center Signup and view all the answers

What is the term for a break in any crystal direction other than a cleavage plane?

Fracture Signup and view all the answers

What is a key difference between inclusions and blemishes in gemstones?

Inclusions are typically features enclosed in or extending into a gemstone. Signup and view all the answers

Which of the following best describes a blemish in the context of gemstone clarity?

A feature confined to the surface of a gemstone. Signup and view all the answers

When examining gemstones, which of the following instruments is emphasized for clarity grading?

A binocular gemological microscope at 10x magnification. Signup and view all the answers

What effect does chromatic aberration have when viewing a gemstone?

It creates a rainbow effect around the viewing field. Signup and view all the answers

How can one differentiate between a blemish and an inclusion when examining a stone?

By observing the light source angle in relation to the facet. Signup and view all the answers

What happens to the depth of field as magnification increases?

The depth of field gets shallower. Signup and view all the answers

What is the significance of recognizing prism images in diamond clarity evaluations?

They result from the strong refraction of diamond. Signup and view all the answers

Which characteristic is NOT associated with internal inclusions in diamonds?

Visible surface scratches. Signup and view all the answers

What type of mineral crystal is most commonly found in diamonds?

Smaller diamond crystals. Signup and view all the answers

Which type of illumination helps to make inclusions stand out against the background of a gemstone?

Darkfield illumination. Signup and view all the answers

Which of the following descriptions accurately represents a bruise on a diamond?

A tiny area of impact that appears cottony in texture. Signup and view all the answers

What distinguishes a knot from other inclusions in a diamond?

It extends to the surface and can look like a raised area. Signup and view all the answers

Which statement about a patch of color on a diamond is true?

It originates as green but can turn brown through heat. Signup and view all the answers

Which of the following describes a cavity in a diamond?

An opening created when part of a feather breaks away. Signup and view all the answers

What is the key characteristic of an indented natural on a diamond?

It consists of growth marks such as trigons or grooves. Signup and view all the answers

How does a laser drill-hole impact a diamond?

It produces a tunnel from the surface to a dark included crystal. Signup and view all the answers

Which option best defines a chip on a diamond?

A shallow opening at the girdle edge or culet with rounded outlines. Signup and view all the answers

What distinguishes fracture filling treatment in diamonds?

It improves appearance by filling laser drill-holes. Signup and view all the answers

What is the effect of the flash phenomenon in a treated diamond?

It shows a color change when the diamond is tilted. Signup and view all the answers

Which of the following best identifies a nick on a diamond?

A shallow opening found along the girdle edge. Signup and view all the answers

What does spherical aberration cause?

linear distortion in the a uncorrected loupe Signup and view all the answers

Study Notes

Clarity Grading in Gemstones

Clarity grading is a crucial aspect of gemstone evaluation.
Clarity characteristics are sometimes called flaws or imperfections.
Two types of clarity characteristics exist: inclusions and blemishes.
Inclusions are features within a gemstone, possibly extending to the surface.
Blemishes are surface-confined features.
Gemstone clarity is assessed systematically.

Examining Gemstones

Initial inspection is through a corrected loupe (10x magnification).
Types of corrected loupes include triplets (to correct color and linear distortions, chromatic and spherical aberration).
Gemstone examination should use achromatic or aplanatic lenses.
Darkfield illumination emphasizes inclusions.
Brightfield illumination highlights inclusions as noticeable dark objects.
Depth of field changes with magnification.
Closeness to a surface reflection indicates proximity to the surface for inclusions.
Prism images, multiple images of inclusions, can arise from strong diamond refraction.
Identifying inclusions vs. blemishes can involve positioning the stone to utilize light from a different angle.

Types of Clarity Characteristics

Internal Inclusions

Minerals (crystals) found within diamonds, with more than 24 identified.
Common crystals include smaller diamond crystals, olivine, and garnet.
Needle-like crystals appear as tiny rods.
Pinpoint inclusions resemble tiny dots.
Clouds are tightly grouped pinpoints, varying in density from hazy to dense.
Twinning wisps are pinpoint groupings in twinning planes.
Internal graining shows crystal growth irregularities, visible in lines or angles, or like transparent threads.
Grain centers are concentrated crystal growth areas.

Surface Reaching Inclusions

Feathers are breaks in the diamond (also called glets in some regions).
Cleavage describes breaks along crystal planes, and fractures are breaks in other directions.
Etch channels are angular openings extending into the diamond.
Bruises resemble tiny impacts with radiating feathers.
Knots are included crystals partially visible on the polished surface.
Patches are naturally occurring radiation stains.
Chips are shallow surface openings.
Cavities are surface openings due to feather or crystal loss during polishing.
Indented naturals are portions of the original surface, with or without growth markings.
Laser drill holes are created by laser beams.
Internal laser drilling expands existing feathers or creates new ones.

Blemishes

Rough girdles are irregular or granular girdles.
Pits are tiny white dots (result from polishing).
Laser manufacturing remnants (LMRs) are surface marks from fabrication processes.
Naturals are original rough diamond surface residue.
Surface graining are transparent surface lines, indicating internal irregularities.
Nicks are small notches.
Abrasions are surface scratches.
Scratches are thin lines.
Extra facets are non-required facets.
Polish marks are feature-like extra facets.
Lizard skin is a wavy surface.
Polishing lines are parallel surface grooves.
Burns are surface haziness from excessive heat.
Dop burns are surface damage from excessive dop (a molten glass substance) heat.

Other Features

Inscriptions on the surface, like logos or text, don't affect clarity unless viewed in 3D.
Surface grooves can be used to mount the diamond.

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Description

This quiz explores the fundamentals of clarity grading in gemstones, focusing on the types of clarity characteristics like inclusions and blemishes. It also covers effective methods for examining gemstones using corrected loupes and different illumination techniques. Test your knowledge on the systematic assessment of gemstone clarity.