The Diamond Crystal (Chapter 7, Key Terms & Key Concept) Flashcards
A solid mass of individual, randomly
oriented crystals, intergrown or held together by a
natural binding agent.
Aggregate
Plane parallel to a possible crystal
face, where a diamond can split cleanly when struck.
Cleavage plane
A chemical bond formed by two
atoms sharing electrons.
Covalent bond
Solid matter with atoms arranged in a
regular, repeating pattern
Crystal
Composed of crystals or related to
crystals.
Crystalline
Internal directions parallel to a
mineral’s unit cell surfaces.
Crystal planes
Geometric shape of a
well-formed crystal.
Crystal shape (form)
Regular, repeating
arrangement of atoms in a mineral.
Crystal structure (lattice)
Categories of crystals based on
their symmetry and internal structure.
Crystal systems
The appearance of double images of a
gemstone’s facet junctions on the side opposite the
viewer.
Doubling
Possessing different
physical or optical properties in different crystal
directions.
Doubly refractive (anisotropic)
A well-shaped, transparent, octahedral
diamond crystal with sharp, square edges.
Glassie
Crystal distortion caused during growth
when one part of the lattice is offset in relation to
the res
Glide plane
Visible, shadow-like lines in
a diamond caused by irregularities in the crystal
structure.
Graining (grain lines)
Characteristic crystal shape of a specific
mineral.
Habit
A flat, triangular twinned diamond crystal.
Macle
A form with eight equal triangular faces
Octahedron
Possessing the same
physical or optical properties in all crystal directions.
Singly refractive (isotropic)
Ratio of the weight of a
material to that of an equal volume of water.
Specific gravity (SG)
In diamond, a group of five carbon
atoms with one at the center
Tetrahedron
The relative ability of a
material to transfer heat.
Thermal conductivity
Capacity of a material to
expand when it’s heated
Thermal expansion
Atoms in a gem that aren’t part of
its essential chemical composition.
Trace elements
Crystal consisting of two or more
intergrown crystals with opposing crystal directions.
Twinned crystal
Smallest group of atoms with the characteristic chemical composition and the basic crystal
structure of a mineral.
Unit cell
Covalent bonds are the strongest of all atomic
bonds.
Key Concepts
Diamond’s atoms are more closely bonded than
the atoms of any other natural material.
Key Concept
The most common habit of gem diamond is the
octahedron, but perfectly shaped octahedral rough
is rare.
Key Concept
Diamonds belong to the cubic or isometric crystal
system, the most symmetrical of the crystal
systems.
Key Concept
Shape is the most important factor in a rough
gem diamond crystal’s potential value.
Key Concept
Cubic planes provide the most efficient sawing
directions for dividing large, regularly shaped
crystals.
Key Concept
The macle is the most common twinned diamond
crystal.
Key Concept
Diamond rough’s potential as a faceted gem
depends on its shape, clarity, and color.
Key Concept
Inclusions can limit a rough diamond’s potential
shape.
Key Concept
The cubic, octahedral, and dodecahedral planes
are the most important directions to a diamond
cutter.
Key Concept
A flat, triangular twinned diamond crystal is called a
macle.
The smallest group of atoms with a characteristic chemical composition and the basic crystal structure of a mineral is called a(n)
unit cell.
The diamond term glassie refers to
a well-formed octahedral crystal.
Another name for the cubic crystal system is
isometric.
Atoms in a gem that aren’t part of its essential chemical composition are called
trace elements.
Solid matter with atoms arranged in a regular, repeating pattern is called a(n)
crystal.
Squares or rectangles, trigons, and parallel grooves are types of
growth marks.
A naturally occurring, inorganic substance with a characteristic chemical composition and usually a characteristic crystal structure is known as a
mineral.
The crystal planes most suitable for cleaving a diamond are the
octahedral planes.
In diamonds, cleavage is caused by
relatively wide spaces between some atomic planes.
Crystal shape is an important factor in the evaluation of rough because
it affects the amount of weight retained after cutting.
Which is the softest crystal direction in diamond?
Dodecahedral
What is the specific gravity of gem-quality diamond?
3.52
The habit of gem-quality diamond is the
octahedron.
The strongest of all atomic bonds are called
covalent.
