Ass # 18- Diamond Simulants

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Questions and Answers

What does a moissanite tester measure?

Refractive index

Thermal conductivity

Electrical conductivity (correct)

Dispersion levels

Which factor does NOT affect the results of thermal conductivity testing?

Touching metals

Temperature of the room

Size of the stone

Color of the stone (correct)

What is indicated if a black synthetic moissanite shows diamond on a thermal tester?

It's definitely a diamond.

It shows false thermal properties.

It has high thermal conductivity. (correct)

It has low thermal conductivity.

How can one examine the dispersion of a gemstone?

By assessing its refractive indices for different wavelengths Signup and view all the answers

What happens during the doubling effect when observing a stone?

Light splits into two beams due to crystal symmetry. Signup and view all the answers

What characteristic of diamonds makes read through testing ineffective?

Small critical angle Signup and view all the answers

Which of the following explains why some simulants might be confused with diamonds?

They have similar thermal conductivity values. Signup and view all the answers

What is a common method for detecting gemstones that requires observing multiple directions?

Doubling observation Signup and view all the answers

Which property do diamond simulants generally lack compared to natural diamonds?

Physical and chemical properties Signup and view all the answers

What is a key characteristic that distinguishes glass as a diamond simulant?

Lower brilliance than diamonds Signup and view all the answers

What process did Auguste Verneuil develop for creating synthetic diamond simulants?

Melting powdered materials over a flame Signup and view all the answers

What term refers to stones that are backed with metal foil, but not all are simulants?

Foilbacks Signup and view all the answers

In testing diamond simulants, what aspect is often evaluated to determine their quality?

Refractive index and dispersion Signup and view all the answers

Which of the following diamond simulants was particularly popular in the 1990s?

Synthetic sapphire Signup and view all the answers

What happens to glass when lead oxide is added to it?

It becomes more brilliant Signup and view all the answers

Which characteristic is not typically found in diamond simulants?

High hardness Signup and view all the answers

When were glass simulants primarily used in jewelry?

Early 1700s Signup and view all the answers

What feature do diamond simulants not consistently replicate?

Physical properties Signup and view all the answers

Which simulant is known to show a bright orange flash on its pavilion facets under darkfield lighting?

Cubic zirconia (CZ) Signup and view all the answers

What is the term used to compare the size of an object to its weight, specifically for loose stones?

Heft Signup and view all the answers

Which characteristic distinguishes diamond from other simulants, making it harder and able to achieve sharp facet junctions?

Exceptional hardness Signup and view all the answers

Why is the pavilion color flash test considered unreliable for certain types of stones?

It is not accurate on fancy cuts or poorly proportioned stones. Signup and view all the answers

What is the specific gravity (SG) range of cubic zirconia (CZ)?

5.80–6.00 Signup and view all the answers

Which type of girdle appearance is common in modern diamonds compared to historical practices?

Polished or faceted girdle Signup and view all the answers

Which of the following inclusions is indicative of natural diamonds but absent in synthetic diamond simulants?

Twinning wisps Signup and view all the answers

Which simulant is noted for having a specific gravity that is slightly lower than that of diamonds?

Synthetic moissanite Signup and view all the answers

What type of luster can simulants achieve compared to the adamantine luster of diamonds?

Subadamantine Signup and view all the answers

What is a common flaw seen in simulants due to their comparative softness compared to diamonds?

Abrasions and scratches Signup and view all the answers

Which statement accurately describes a common feature of diamond simulants?

They are generally eye-clean and lack many inclusions. Signup and view all the answers

What is a correct approach when accepting jewelry for repair without knowing the material?

Use a neutral description for the take-in form. Signup and view all the answers

Which of the following simulants is known for being heavily promoted and commonly recognized?

Synthetic cubic zirconia Signup and view all the answers

What characteristic should a jewelry professional exhibit to encourage clients interested in simulants?

A positive attitude that builds trust and satisfaction. Signup and view all the answers

What is a significant risk when selling gems without accurate identification?

Overestimating the gem’s value based on assumptions. Signup and view all the answers

What property of CZ gives it a closer appearance to diamonds?

Higher dispersion Signup and view all the answers

Which characteristic differentiates synthetic moissanite from CZ?

Synthetic moissanite tends to have a yellowish or greenish tint Signup and view all the answers

What is an important feature of assembled simulants?

They are made up of two or more components Signup and view all the answers

How can one easily detect garnet-and-glass doublets?

By rocking the jewel back and forth under light Signup and view all the answers

What distinguishes coated simulants from standard CZ or synthetic moissanite?

They have additional coatings of synthetic diamond particles Signup and view all the answers

Which quality does synthetic moissanite possess in comparison to diamond?

Greater fire Signup and view all the answers

What aspect implies the low heft of synthetic moissanite?

Low specific gravity relative to diamonds Signup and view all the answers

What makes color in CZ differ from natural colored diamonds?

CZ colors are more saturated Signup and view all the answers

What is a major challenge in identifying synthetic moissanite?

It can imitate black diamonds effectively Signup and view all the answers

What is the typical Mohs scale rating for synthetic moissanite?

9.25 Signup and view all the answers

Study Notes

Diamond Simulants

Simulants have been used in jewelry since the late 1800s, offering affordable alternatives to natural diamonds.
Simulants lack the physical and chemical properties of diamonds, varying widely in their characteristics.
Simulants can be natural or manufactured, including glass (paste), foilbacks (using mirroring films), rhinestones, synthetic sapphires/spinels, zircon, rutile, strontium titanate, YAG, GGG, cubic zirconia, and moissanite.

Attributes of Diamond Simulants

A successful simulant mimics diamond's appearance (color, brilliance, and clarity).
No simulant can perfectly replicate all diamond properties.
Popular simulants include glass, foilbacks, rhinestones, synthetic sapphires, spinels, zircon, rutile, strontium titanate, YAG, GGG, cubic zirconia, and moissanite.

Popular Diamond Simulants

Glass/Paste: Effective diamond imitations since the 1700s, enhanced with lead oxide for brilliance. Lower brilliance, luster, and hardness than true diamonds.
Foilbacks: Stones backed with metal foil (or mirroring films); commonly used as imitations.
Rhinestones: A trade term for diamond imitations, often made of glass or plastic.
Synthetic Sapphire/Spinel: Popular in the late 1800s, created through a process of melting powdered materials over a flame and cooling them.
Zircon: A natural gem occurring in various colors, colorless forms became more common through heat-treating. More brilliant than glass with medium fire, but brittle and scratches easily.
Synthetic Rutile: Briefly used as a simulant in the 1940s; yellowish body color, but strong fire and high dispersion.
Strontium Titanate: Introduced in 1953, singly refractive, similar color to diamonds but less durable due to low hardness.
YAG (Yttrium Aluminum Garnet) / GGG (Gadolinium Gallium Garnet): Lab-grown, garnet-like materials, YAG has good hardness, and GGG has better fire.
Cubic Zirconia (CZ): Extremely popular modern simulant, almost as brilliant and has high dispersion, but can come in a variety of different colors.
Synthetic Moissanite: A convincing simulant with slightly less brilliance than a diamond but higher fire and luster.

Identifying Simulants

Thermal Conductivity Testing: Diamonds have higher thermal conductivity; thermal testers measure the rate of surface temperature changes.
Electrical Conductivity: Moissanite conducts electricity; moissanite testers use electrical currents to detect the material.
Doubling: Some materials when viewed through a loupe split light into two beams (double refraction).
Dispersion: The difference in the refractive index between red and violet wavelengths of light (fire).
Read-Through: Diamonds have relatively small critical angles preventing light from passing through; simulants often have larger critical angles.
Pavilion Flash: Simulants may exhibit color flashes on their pavilion facets when using darkfield lighting.
Specific Gravity and Heft: The ratio of a substance's density to the density of water, some simulants are typically heavier than a diamond.

Other Considerations

Hardness, Luster, and Polish: Diamonds are harder than any natural or manufactured simulant. Simulants may show signs of wear easily.
Inclusions and Blemishes: Natural diamonds may have inclusions (imperfections); simulants rarely exhibit these inclusions.
Mistakes and Deceptions: Be wary of exaggerated or false claims when purchasing simulants. Always verify the material's true nature before accepting jewelry from someone.
Staying Current: Knowledge and skills are crucial in identifying new tricks and identifying simulants.

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Description

Explore the fascinating world of diamond simulants, which have provided affordable alternatives to natural diamonds since the late 1800s. This quiz covers various types, attributes, and popular choices among simulants, such as cubic zirconia and moissanite. Discover how these imitations mimic the appearance of diamonds while lacking some physical properties.