Cleavage and Parting in Gemstones
The term "cleavage" refers to the splitting, or parting of a mineral along defined "planes" that are related their crystalline structure.
Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: ...
Common Cleavage Patterns
Octahedral (4 cleavage planes)
Prismatic (2 cleavage planes / 3rd direction shows fracture) ...
Cleavage
Breaking, or tendency to break, of a stone along lines of weakness related to the internal atomic structure.
Jewelry Frequently Asked Questions
How can I test pearls and care for them?
Diamond Cleavage
In the world of minerals and gemstones, cleavage is defined as "the tendency of a crystallised mineral to break along certain definite directions producing more or less smooth surfaces" (Webster).
Cleavage: This property refers to the ability of a crystal to break along certain specific planes with a lot more ease when compared with the other directions. Naturally crystals can break either perfectly or imperfectly.
Cleavage: Breakpoint or weakness of a gem, connected to its atomic structure. Ironically, gems defined as having perfect cleavage are the ones most likely to break when being cut or faceted.
Cleavage: The propensity of crystalline minerals, such as diamond, to split in one or more directions either along or parallel to certain planes, when struck by a blow.
Cleavage
The breakpoint or weakness of a gem, connected to its atomic structure. Most gems with perfect cleavage are more likely to break when being cut or faceted.
Cleavage
A break in a diamond which is parallel to the diamonds crystal planes. A cleavage may be caused by internal strain or a sharp blow.
Cloud ...
CLEAVAGE - The tendency of a crystalline mineral to break in certain definite directions called cleavage planes. The breakage is done by cleaving, a process where a stone is studied so that the plane may be defined and divided with a swift blow.
Cleavage - Among gemstones, cleavage refers to the act of splitting or the tendency to break parallel to certain flat planes. Cleavage is rarely entirely on one level but can have a step like appearance.
Cleavage cracks
These occur in the direction of the cleavage planes parallel to the four octahedral faces.
Cleavage and Fracture:
Cleavage and fracture refer to the characteristic manner in which gems will break when an external force or stress is applied.
Cleavages
Cleavages are usually a break in a weak spot in the Diamond.
Fractures ...
Cleavage
Cleavage are natural breaks that occur due to the formation of the crystallized structure.
Clip-on
Clip-on is a piece of jewelry that is fastened by a clip and does not require piercing, i.e. clip on earrings.
Cleavage: A natural area of the diamond where a weak bond holds the atoms together. The gem will be split along these planes by the cutter.
Cleavage: none
Fluorescence: Frequently shows a strong light blue to blue green to LW UV and a weaker reaction to SW UV ...
Cleavage: A term to describe a break within a diamond. Usually the cleavage crack extends to the surface. It is the most damaging kind of imperfection in a diamond, since it affects durability as well as beauty.
Cleavage
A smooth, flat break or separation in a gem along the direction of its atomic structure.
Cloud/Cloudy
A group of small, white inclusions that give a cloudy appearance to a diamond.
Cleavage The plane of weakness of some gems where they will split apart with smooth surfaces. Gems with perfect cleavage are likely to break when being cut or faceted.
CLEAVAGE. Direction within a crystal along which there is minimum cohesion; diamond crystals which require cleaving; pieces cleaved from the crystal.
cleavage feather Internal imperfection (inclusion) that sometimes resembles a bird's feather and runs parallel to the cleavage plane (octahedral face) of the diamond.
CLEAVAGE
Cleavage is the natural in which way a mineral breaks, along certain planes based on its internal crystalline structure.
CLOISONNE ...
Cleavage: The property of many crystalline gemstones to split readily in one or more directions along certain planes when subjected to a blow.
Cleavage: Cleavage is the tendency which a stone has to fracture along its crystal structure.
Clip-on: A piece of jewelry designed to be attached by means of a clip, such as a clip-back earring.
Cleavage
The breaking of stones along lines of weakness related to the stones internal atomic structure.
Clip-on Earrings ...
Cleavage
Top
A cleavage plane is a plane of structural weakness along which a mineral is likely to split smoothly. Cleavage thus refers to the splitting of a crystal between two parallel atomic planes.
Cleavage is important to consider in this system. If there is a good pinacoidal cleavage parallel to the b axis (as in the mineral orthoclase), then it is usually called the basal cleavage.
Cleavage
Usually describes an internal crack or break in a diamond along a cleavage plane.
Colorless ...
Cleavage
The tendency shown by certain stones to split along one or more defined directions. Cleavage planes are always parallel to the crystal faces.
Cleavage: perfect, octahedral (4 directions)
Specific Gravity: 3.514 - 3.518
R.I.: 2.4175 in sodium light; one of the highest R.I.s of any gem material.
Cleavage...The tendency of stones to split along one or more definite directions, always parallel to a possible crystal face.
Conchoidal..(fracture), A breakage which leaves a conchoidal shell shaped surface.
Cleavage:
one perfect (Joel Arem); three perfect (Richard T. Liddicoat)
Fracture: ...
Cleavage is the natural way in which a gemstone has the tendency to break along its crystal structure.
CLOUDS ...
Cleavage
Imperfect to distinct in one direction (rarely seen)
Specific Gravity ...
Cleavage is a physical property of gemstones that is related to structure. It is a break that occurs along certain planes of growth, and is a function of the cohesive properties of atoms, or groups of atoms within the crystal lattice.
Cleavage: The natural tendency of a stone to break according to it's crystal structure.
Cliché: A steel raised pattern of a design to be made eventually in silver.
Cleavage, fracture, and parting. Because bonding is not of equal strength in all directions in most crystals, ...
Feathers: cleavages or fractures often white and feathery in appearance. (There are 4 cleavage planes in diamond, which run in octahedral directions.
A small, curved, cleavage inclusion, normally emanating from the gem's surface.
Clarity ...
Topaz has perfect cleavage in one direction, so carvings are rare. When they do occur, especially by known artists, they are soon collected.
Care & Collecting ...
Due to the perfect cleavage of this stone, handle it with great care.
The color of tanzanite is most intense in sizes above ten carats. Smaller tanzanites are usually pale in color.
Chanthaburi ...
Kyanite has perfect cleavage in one direction. This combined with its varying hardness (kyanite is extremely unusual, displaying two hardnesses within one gem), makes kyanite a challenging gem to facet.
The gem is characterized by its glassy luster, lack of cleavage, and hardiness of 7 on the Mohs Scale. Ametrine is said to bring mental and physical clarity and harmony, bolster the immune system, and enhance intuition and creativity.
Have perfect rhombohedral cleavage
3. Exhibit a very strong double refraction in transparent rhombohedrons caldera A vast depression at the top of a volcanic cone, ...
Topaz has perfect cleavage, making it susceptible to splitting if struck upon a hard surface. Consequently, topaz beads should be protected from knocks. Also avoid large temperature changes (such as leaving it beside a heater vent or in a hot car).
The generic term "feldspar" comes from the Germanic term "feldt spat", meaning "mineral with prominent cleavage from the field". It was a prime constituent of many of the rocks over turned by farmers while plowing their fields.
Summer 1942, (Cleavage-Cutting Centers), p. 29, 4pp.
Fall 1942, (Cutting, History of-Dyke), p. 43, 4pp.
Winter 1942, (Eclogite-Fracture), p. 59, 4pp.
Spring 1943, (Fromesite bort-Holland Rose Cut), p. 73, 4pp.
These stones have no noticeable cleavage and are exceedingly tough, for minerals, as well as very hard. We have only to consider the use of impure corundum (emery) as a commercial abrasive in emery wheels, emery cloth, emery paper, etc.
Cleavage - Planes in a crystal which are easily split.
Cleavage Face - A face on a specimen caused by cleavage, rather than natural growth.
Columnar - Like a column. Usually referred to in groups of parallel, rod-shaped crystals.
It does posses a very strong cleavage, which makes cutting and handling a challenge. As a result, it can be split with a single blow, a trait it shares with diamond. As a result it should be protected from hard knocks.
In addition, cubic zirconia doesn't share the diamond's one fundamental weakness - cleavage. A diamond has four directions of ‘perfect cleavage', and if struck from any of those directions, it will split.
Ruby has no cleavage but has preferred directions of parting. Inclusions are common and not an indication of lower quality.
It is known to have 'four directions of cleavage'. If it is hit in any of these four directions, diamond will break easily. Its melting point is 3820K. Its density is measured as 10 in the Mohs hardness scale.
Brittle, with one direction of perfect cleavage. Although heavily promoted by the jewelry industry for widespread use, tanzanite is really too fragile for use in rings that are worn daily, where it can quickly become scratched and chipped.
It wears well in jewelry but care must be used if it is set in rings because of its very strong cleavage.
the Koh-I-Noor had a flaw near the summit which, being on a line of cleavage parallel to the upper surface, may very possibly have been produced when the upper portion was removed -- the weight of which, ...
To the chagrin of the cutters, however, this gem has perfect cleavage and is thus extremely difficult to cut. Having said that, once it has been given its final shape, it becomes uncomplicated. But it is very difficult to re-cut.
The nondurable stones are too soft, therefore subject to scratching and abrasion, are brittle or contain cleavages, therefore are fragile and subject to breaking, or are both soft and fragile. Some of the rare collector/specialty stones from U. S.
 See also: Stone, Crystal, Color, Gemstone, Mineral
|
