GIA-DDG 19 Flashcards
An industrial process adapted to allow growth of synthetic diamond from carbon-rich gas in thin layers onto a silicon or diamond surface
Chemical Vaport Deposition (CVD)
Graphite formation around a diamond’s mineral inclusions and feathers that results from the extreme conditions of HPHT processing
Graphitization
The length of time required for half of a group of atoms of a particular type (radioactive) to decay into another type (non-radioactive)
Half-life
Diamond synthesis method that mimics the pressure and termperature conditions that lead to natural diamond formation
High pressure, high temperature (HPHT)
A clarity treatment that uses a laser to expand an existing cleavage or create a new one, allowing the introduction of a bleaching solution
Internal Laser Drilling (ILD)
Exposure of a material to radiation; causes color change in diamonds
Irradiation
Using a concentrated bead of laser light to reach a diamond’s dark inclusions and disguise or eliminate them
Laser Drilling
A machine used to accelerate electrons to high energy along a straight path
Linear accelerator
Manufactured diamond with essentially the same physical, chemical, and optical properties as natural diamond
Synthetic diamond
Synthetic diamond is a
manmade diamond with essentially the same physical, chemcal, and optical properties as natural diamond
The use of synthetic diamonds in jewelery
is limited by high production costs
Most synthetic gem-quality diamonds are
yellow or brown
Which one of the following clarity characteristics might be found in a synthetic diamond?
Metallic flux
Which one of the following is typical of the UV fluorescence of synthetic diamonds
yellow to greenish yellow under both longwave and shortwave
which one of the following is used today to safely color-treat diamonds
high-energy electrons in a linear accelerator
GIA laboratory and other gemological laboratories
don’t grade facture-filled diamonds
Annealing irradiated diamonds can produce
brown, orange, or yellow
Annealed diamond color can change if it’s exposed to
heat during routine repairs
The origin of a diamond’s color
should usually be determined by a gemological laboratory
Scientists successed in producing synthetic industrial diamonds for the first time in the
1950s
Which one of the following is an indication of the HPHT process?
Etched or frosted naturals–also Hourglass graining
Laser drill-holes
become permanent clarity characteristics
Color treating diamonds in a linear accelerator produces
blue or blue-green colors
The flash effect proves that a diamond
is fracture-filled
What is the most common diamond treatment?
Fracture Filling
T/F-The use of synthetic diaonds in jewelry is limited by high production costs
True
What are 3 ways HPHT synthetic diamonds can be identified?
- Metallic flux inclusions
- Growth structures (hourglass graining)
- Fluorescence (yellow to greenish yellow under both longwave and shortwave UV)
Other ways:
- Phosphorescent
- Attracted to magnet
What are colors of CVD synthetic diamonds?
- Faint brown to dark brown
- Near-colorless to colorless
- Light blue to intense blue
What are ways to detect CVD synthetic diamonds?
- By color
- Small, irregularly shaped black inclusions (graphite)
- lack flux metal inclusions common in HPHT synthetics
- May flouresce a very weak yellow-orange under long wave UV
What is DiamondSure and DiamondView?
Developed by De Beers in the mid-1990s. Can separate natural from synthetic colorless or near-colorless diamonds based on the way each absorbs light. Can test both mounted and unmounted gems. Diamonds that don’t pass the DiamondSure’s test can be positively identified by the DiamondView.
What are some signs of fracture filling?
- Flash effect
- Trapped Bubbles
- Crackled texture
