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85 Cards in this Set
- Front
- Back
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What are the two main categories of synthetic-gem production methods?
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Low cost, High Volume
Low Volume, High Cost |
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Why is quartz synthesis important?
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It plays a key role in technology. It can generate an electric current when placed under pressure or vibrate in precise response to alternating current.
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Synthetic comes from the Greek for ____ ______
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Put Together
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Which synthetic gem type can be made using a wide variety of processes
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corundum
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Define melt process
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A synthetic-crystal growth method in which the chemical mixture is melted then recrystallized
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Define solution process
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A growth method in which the synthetic crystal grows from a dissolved chemical mixture, sometimes at high temperature and pressure
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Define Flame fusion
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A process in which powdered chemicals are dropped through a high-temperature flame onto a rotating pedestal to produce a synthetic crystal
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Define Pulling
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A process in which the synthetic crystal grows from a seed that is dipped into a chemical melt, then pulled away as it gathers material.
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Most methods used for synthetic gem production today derive from which two main types of processes
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melt and solution
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The two most common melt processes are
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flame fusion and pulling
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Define boule
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A cylindrical synthetic crystal produced by flame fusion
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Who produced the first synthetic ruby using flame fusion in the early 1900's
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Auguste Verneuil
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Give the basic steps of flame fusion
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-Powdered chemicals drop through a high temp flame onto a slowly sinking and rotating pedestal.
-The melted chemicals cool, then crystallize. -The synthetic crystal forms an elongated boule |
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What was the fist method to result in a marketable synthetic...And what was the synthetic
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Flame Fusion
Verneuil's gem-quality ruby |
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How quickly do flame fusion crystals grow?
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Quickly: Approx 1cm/hour
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Is Flame Fusion:
low cost, high volume or high cost, low volume |
Low cost, high volume
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Synthetic colored stones made by flame fusion include ___ ____ _____ _____ and ____.
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Ruby
Star Ruby Sapphire Star Sapphire Spinel |
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_____ a diamond imitation is also made by flame fusion
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Rutile
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What is the MAIN method used to synthesize gems today
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Flame fusion
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Define seed crystal
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A tiny crystal used as a template to control the size, speed, or direction of growth and the shape of a growing synthetic crystal
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Pulling is also known as the _______ method, after its creator
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Czochralski
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Pulling emerged as a way to produce a synthetic ruby with ________ than a flame fusion ruby
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fewer internal growth marks / inclusions
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Describe the basic pulling process
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-powdered ingredients are melted in a crucible
-A tiny seed crystal is attached to a rod that touches the melt's surface -As the rod rotates and slowly pulls up out of the melt, it pulls some of the mixture with it -The melt mixture on the rod cools and crystallizes forming a cylinder |
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How big can a pulling cylinder get?
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up to 4" in diameter and more than 16" long
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How big can a flame fusion boule get?
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about 1-2" in diameter and up to 9" long
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Which is larger? A pulling cylinder or flame fusion boule?
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Pulling
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How rapidly can pulled synthetic crystals form
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10cm/hour
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Which has fewer inclusions:
Flame Fusion Pulling |
Pulling
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Which process produces the covers for watch faces and the windows on supermarket bar code readers?
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Pulling
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gems synthesized by pulling include:
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alexandrite, cat's eye alexandrite, green chrysoberyl and the corundums: ruby, star ruby and sapphire
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Pulling also produced ___ and ___ two manmade crystals that once served as diamond imitations
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YAG: ytrium aluminum garnet
GGG gadolinium gallium garnet |
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define floating zone
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a melt process where a heating unit passes over a rotating solid rod of chemicals until it forms a synthetic crystal
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Floating zone was developed in ____ in response to a need for high quality _______ _________
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1953
silicon semiconductors |
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Define the basic way the floating zone works
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-A mixture of the components necessary to make up the desired crystal is merged together into a rod-shaped solid
-As the rod rotates, a heating unit passes over it causing the material to crystallize in zones -Eventually, this transforms the rod into a single crystal |
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In the 1980s which Japanese company used the floating zone while attempting to make a better watch crystal?
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Seiko
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Which synthetic gems did Seiko once produce
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Ruby, sapphire and chrysoberyl
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Define skull melt
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A synthetic crystal growth method that uses cooling pipes around an interior of melted chemical ingredients
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What gem is produced by the skull method
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Synthetic cubic zirconia
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What is the best selling diamond imitation?
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Cubic zircoia
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Define the basic process of Skull melt method
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-A shell of water cooled copper pipes (The Skull) circulates zirconium oxide powder to keep the outer layer cool
-Heat from radio frequency coils melts the inner material which crystallizes -Colors are made with various additives |
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Which processes can synthesize gems that closely resemble natural gems?
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Solution
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Solution processes are generally _____ (Speed) and _______ (Cost) than melt processes
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slower and more expensive
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What is one way that solution processes differ from melt processes?
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The ingredients used in solution don't necessarily match the composition of the crystals being made.
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What happens to quartz during the melt technique
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They don't crystallize when they cool: They combine into a thick, semi-fluid glass
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What happens to emeralds during the melt technique
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the chemical components melt at different temps, so they cool at separate rates into 3 distinct materials.
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What are the 3 materials emeralds form during the melt process
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phenakite
chrysoberyl quartz |
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What are the two common solution processes?
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Flux
hydrothermal |
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define flux growth
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A process in which nutrients dissolve in heated chemicals then cool to form synthetic crystals
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define hydrothermal growth
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A process in which nutrients dissolve in a water solution at high temperature and pressure, then cool to form synthetic crystals
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Who began marketing flux-grown emeralds in the 1930s
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Carroll Chatham
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Name some flux grown gems
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emerald
rubies sapphires alexandrites spinnels |
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How long can crystal growth take during the flux process
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up to a year
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What is a characteristic inclusion of synthetic emerald grown by flux
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fingerprint-like inclusions made up of flux droplets
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Define spontaneous nucleation
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a synthetic crystal growth method that starts without a seed crystal
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The flux process requires a ____ that resists corrosion and can withstand high temps
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crucible
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What material makes the best flux crucible?
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Platinum
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Flux is:
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A solid material that when melted dissolves other materials in the same way that water dissolves sugar
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What size crystals from during the flux process
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.5cm to 7.5cm in diameter
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What is the only method for successfully growing synthetic quartz?
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hydrothermal growth
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What is the steel container used in the hydrothermal process called?
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an autoclave
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What size hydrothermal quartz crystals can form?
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up to 18" long and 6" in diameter
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Define the basic hydrothermal process
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-within a steel autoclave, nutrients dissolve in a solution of water and chemicals at high temp and pressure
-As the solution rises to the top it cools and tathers new material forming synthetic gem crystals on from seed crystals suspended above. |
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Scientists use quartz for
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watches, clocks, communications equipment, filters and oscillators
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What does hydrothermal emerald use as a seed crystal?
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synthetic beryl
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Which 2 countries have marketed synthetic hydrothermal corundum
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Russia and Thai growers in Bangkok
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What do Russian growers use as a coloring agent to get a consistent blue in hydrothermal sapphire
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nickel
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In the 1970s who achieved a believable synthetic opal?
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The Gilson company
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What is the formation process for a synthetic opal called
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The three step process
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What are the names of the 3 steps of synthetic opal formation
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1: Precipitation-A chemical process that produces microscopic silica spheres of identical size
2: Settling: The spheres settle in acidic water 3: Hydrostatic: Water in a hydrostatic press compresses the material |
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How long do opal spheres "Settle" in acidic water
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Over a year
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what is the characteristic pattern of a synthetic opal look like?
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Honeycomb or snakeskin
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Define ceramic process
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a process in which finely ground powder is heated, sometimes under pressure, to produce a fine-grained solid material
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What is the process that Gilson used to produce synthetic turquoise and imitation lapis
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Ceramic
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The presence of gas bubbles is a clue that a colored stone is:
Natural or synthetic? Why? |
Synthetic.
Because: In natural gems, gas bubbles only appear as part of a 2 or 3 phase inclusion. |
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In most natural gems, growth marks are always _____ or ______. Never ________________.
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Straight or angular.
Never CURVED. |
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Imitations need only ______________ the gem they're supposed to replace
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look like
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What gems can be called alternative
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natural imitations without the intent to deceive buyers.
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What is a popular age-old gemstone imitation?
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Manufactured glass
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define assembled stone
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two or more separate pieces of material joined to form a unit
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define doublet
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Two separate pieces of material fused or cemented together to form a single assembled stone
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define triplet
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a single assembled stone made from three separate pieces of material fused or cemented together or from two pieces and a colored cement layer
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Assembled stones are also called
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composite stones
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which natural stone is often an assembled stone due to its thin layers
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opal
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Synthetics and imitations offer consumers
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An affordable alternative to fine colored stone jewelry
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define disclosure
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clearly and accurately informing customers about the nature of the goods they buy
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