Laboratory-Grown Diamonds and Treatments (Chapter 19, Key Terms & Key Concepts) 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 vapor deposition (CVD)
Graphite formation around a
diamond’s mineral inclusions and feathers that
results from the extreme conditions of HPHT
treatment.
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 temperature 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 beam 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 (synthetic)
diamond with essentially the same physical,
chemical, and optical properties as natural diamond.
Lab-grown diamond
Diamond’s beauty, rarity, and value inspire research into
synthesis and treatment.
Key Concept
Research into diamond synthesis began before 1800, but
producers didn’t succeed until the 1950s.
Key Concept
Lab-grown diamonds are better for many industrial applications
than natural diamonds.
Key Concept
The use of lab-grown diamonds in jewelry is limited by high
production costs.
Key Concept
Most HPHT synthetic diamonds are yellow or brown because
they contain nitrogen impurities.
Key Concept
HPHT synthetic diamonds can be identified by their metallic
flux inclusions, growth structures, and fluorescence.
Key Concept
CVD synthetic diamonds lack the flux metal inclusions that
might be seen in HPHT synthetic diamonds.
Key Concept
Modern diamond irradiation methods leave little or no color
zoning and no radioactivity.
Key Concept
Heat can alter irradiated colors.
Key Concept
Annealed diamond color can change if it’s exposed to heat
during routine repairs.
Key Concept
HPHT eliminates the structural distortions that cause brownish
coloring in some Type IIa diamonds.
Key Concept
HPHT can dramatically improve the color and value of
brownish diamonds.
Key Concept
Most origin-of-color tests should be done by a gemological
laboratory.
Key Concept
Laser drilling can make a diamond more marketable by
improving its appearance.
Key Concept
Because laser drill-holes are permanent, gem labs report
them as clarity characteristics.
Key Concept
Fracture filling makes a diamond’s fractures less reflective by
using a high-RI glass filler.
Key Concept
Fracture filling is the most common diamond treatment.
Key Concept
Some signs of fracture filling are the flash effect, trapped
bubbles, and a crackled texture.
Key Concept
Disclosure of fracture filling is an industry requirement.
Key Concept
