Ass 17 - Diamond Treatments Overview

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Questions and Answers

What is the effect of color zoning in a cyclotron-irradiated diamond?

It causes an umbrella-shaped color zone around the culet. (correct)

It leads to increased fluorescence.

It creates a uniform color throughout the diamond.

It enhances the diamond's clarity.

How is half-life relevant to understanding radioactivity in materials?

It shows the average stability of radioactive isotopes.

It defines the lifespan of gemstones.

It measures the time required for half of the radioactive atoms to become nonradioactive. (correct)

It indicates the time taken for all radioactive atoms to decay.

What happens to carbon atoms when a diamond is irradiated?

They become entirely nonradioactive immediately.

They transform into nitrogen atoms.

They increase the diamond's hardness.

They are displaced and create vacancies in the crystal lattice. (correct)

Which type of diamond has nitrogen impurities that can lead to a yellow bodycolor?

Type I diamonds Signup and view all the answers

What is the primary result of irradiating Type IIa diamonds?

They create a GR1 defect without yellow bodycolor. Signup and view all the answers

What role does annealing play in the treatment of diamonds after irradiation?

It redistributes vacancies and impurities in the crystal lattice. Signup and view all the answers

Which instrument is commonly used to detect moderate to high levels of radioactivity?

Geiger counter Signup and view all the answers

What characteristic distinguishes Type II diamonds from Type I diamonds?

Type II diamonds have negligible nitrogen impurities. Signup and view all the answers

What is the primary visual evidence of fracture filling in diamonds?

Flash effect Signup and view all the answers

Which of the following colors is most commonly seen in darkfield lighting when observing fracture-filled diamonds?

Orange Signup and view all the answers

Why do gemological laboratories like GIA not grade fracture-filled diamonds?

The process of filling is semipermanent. Signup and view all the answers

What is the main goal of diamond color treatments?

To create or remove color in lower-value diamonds Signup and view all the answers

Which range of the D-to-Z color scale is typically chosen for color treatments?

Brown or light yellow Signup and view all the answers

What is the process called when a material is exposed to radiation?

Irradiation Signup and view all the answers

What makes irradiation considered a permanent treatment for diamonds?

The color cannot revert to its original state. Signup and view all the answers

What major advancement in irradiation treatment occurred shortly after World War II?

Development of the cyclotron Signup and view all the answers

What typically occurs to diamonds due to natural radiation in the ground?

They turn green. Signup and view all the answers

Which characteristic is NOT typically associated with fracture-filled diamonds?

Iridescence Signup and view all the answers

What primary colors can type Ia irradiated blue-green diamonds be transformed into?

Yellow, orangy yellow, yellow-green, or brown Signup and view all the answers

Which of the following best describes type Ib diamonds?

Extremely rare with a strong brown component Signup and view all the answers

How can the color of green diamonds be classified?

Natural or artificial, often indistinguishable with tests Signup and view all the answers

What significant effect does HPHT treatment have on diamonds?

Reorganizes defects within the diamond's crystal lattice Signup and view all the answers

What is the primary method for detecting color treatments in diamonds?

Microscopic examination with diffused lighting Signup and view all the answers

What specific change occurs to diamonds after HPHT treatment?

They exhibit significant etching and pitting Signup and view all the answers

What color change did the Deepedene Diamond undergo after being treated?

From light yellow to green Signup and view all the answers

Which defects are commonly created in type Ia diamonds through irradiation and annealing?

H3 and H4 defects Signup and view all the answers

Which statement about color treatment in diamonds is FALSE?

Color changes are always permanent Signup and view all the answers

Why is the Deepedene Diamond historically important?

It has a notable ownership lineage and transformation Signup and view all the answers

What is the primary purpose of fracture filling in diamonds?

To improve the diamond's apparent clarity Signup and view all the answers

How does the refractive index (RI) of a filler used in fracture filling compare to that of air?

It is closer to that of diamond than air Signup and view all the answers

What effect can common jewelry repair procedures have on filled diamonds?

They can damage the filler used in the fractures Signup and view all the answers

What characteristic of diamonds that have undergone laser drilling may be observed under magnification?

A step- or worm-like series of channels Signup and view all the answers

Which type of dark inclusion is best suited for internal laser drilling?

Surface-near dark inclusions Signup and view all the answers

What is the primary effect of HPHT treatment on type I diamonds?

It induces new color centers and removes undesirable hues. Signup and view all the answers

Which laboratory technique is essential for detecting HPHT-treated diamonds?

Photoluminescence spectroscopy Signup and view all the answers

What is a common outcome of irradiation as part of a multi-step treatment on diamonds?

It creates GR1 defects, which affect color. Signup and view all the answers

What color is best achieved through LPHT treatment in diamonds?

Black Signup and view all the answers

Which treatment method is specifically associated with the creation of highly valued pink diamonds?

Combination of HPHT and irradiation Signup and view all the answers

What effect does the formation of graphite around a diamond's inclusions indicate?

It has undergone HPHT treatment. Signup and view all the answers

What combination of treatments is typically used for achieving a blue diamond color?

HPHT treatment followed by irradiation Signup and view all the answers

Which statement about coatings on diamonds is true?

Coatings can be composed of various trace elements like silver and gold. Signup and view all the answers

What is the function of annealing in diamond treatments?

To stabilize color changes caused by irradiation. Signup and view all the answers

What outcome does HPHT treatment have on type IIa diamonds?

It releases vacancy clusters causing brown bodycolor. Signup and view all the answers

Study Notes

Diamond Treatments - Clarity

Laser Drilling: Used since the 1970s to mask or remove inclusions. A carbon dioxide laser drills tiny tunnels to allow acid to remove or vaporize inclusions. This process leaves channels.
Laser Drilling Detection: Drill holes are typically located on crown facets and appear as tiny channels/feathers (black or white) under magnification.
Fracture Filling: Introduced in the 1980s, fracture fillings infuse a molten glass into diamond fractures to reduce visibility. The refractive index of the filling is close to that of a diamond.
Fracture Filling Detection: The flash effect, a change in color (orange, pink, purple, violet, or bluish-green-to-greenish-yellow) is often visible. Other signs include flattened gas bubbles, flow-like structures, or a crackled texture.

Diamond Treatments - Color

Goal: To improve the appearance of lower-value diamonds by mimicking higher-value colors. Value declines as color increases on the D-to-Z scales.
Irradiation: A process where diamonds are exposed to high-energy electrons (linear accelerators). This treatment is permanent (color doesn't revert). Color results depend on the initial diamond's material
Cyclotron Irradiation: A large machine that accelerates atomic particles in a circular path, enabling laboratory diamond irradiation at a commercial level. Evidence is color zoning parallel to facet junctions.
Half-Life: Time required for half of a radioactive substance to decay. Useful for measuring the period of radioactivity in materials.
Geiger Counter: A device for measuring radioactivity. Used to estimate amounts in a material.
HPHT (High-Pressure/High-Temperature): A treatment that moves and rearranges colour defects in a diamond's crystal structure, potentially creating or removing color. This technique can cause etching and pitting on the surface which requires repolishing. Can create yellow, orange, or yellow-green hues in Type Ia. It does not create new colours in Type IIa.
Annealing (Post-Irradiation): Controlled heating and cooling to allow vacancies and impurities to move in the crystal lattice, which modifies the color from irradiation.
Multi-Step Treatments: Combine HPHT, irradiation, and annealing to achieve specific colours like pink or blue.
LPHT (Low-Pressure/High-Temperature): Similar to HPHT but used to create a specific black colour through graphitization.

Detection Methods

Gemological Microscopy: Helps in identifying treatment by detecting visible treatment signs under magnification.
Advanced Laboratory Techniques: Photoluminescence spectroscopy can identify HPHT treatments.
Color Concentration: Can be unevenly distributed, concentrated around the culet or confined to the surface of a facted diamond, suggesting treatment.
Microscopic Examination: Necessary for finding treatment evidence, combined with diffused lighting and immersion.

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Description

Explore various treatments used to enhance diamond clarity and color. This quiz covers methods like laser drilling and fracture filling, along with their detection techniques. Understand the goal of color treatments and their impact on diamond value.