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Diamond Mining Glossary

Diamond Mining Terms and Definitions

Everything you need to know about Diamond Mining. Be sure to check out our Diamond Terms and Definitions.

Aeromagnetic Survey

An airborne geophysical survey using a magnetometer.


A Kimberlitic rock chiefly composed of biotite or phlogopite and melilite as essential minerals, commonly with olivine, calcite, and clinopyroxene.

Alluvial Diamonds

Diamonds that have been washed into and remain in a deposit of clay, silt, and sand left by flowing water in a river valley or delta.


A feature distinguished by geological, geophysical, or geochemical means, which is different from the general surroundings, and which may be indicative of a zone of potential diamond exploration interest.


Refers To an earlier part of the Precambrian aeon (before or about 2,500 million years ago).

Assessment Work

The amount of work specified by diamond mining law, that must be performed each year in order to retain legal control of mining claims.


A rock made up of highly angular coarse fragments. May be sedimentary or formed by crushing or grinding along faults.

Bulk Sample

A large sample consisting of hundreds of tons which is then processed to determine grade.


A unit to measure the weight of a diamond.


A non-metallic element, found free in nature in three allotropic forms: amorphous, graphite, and diamond.

Caustic Fusion

A process which utilizes attrition milling, heavy liquid separation and complete digestion of the rock by subjecting it to strongly basic solution at high temperature(caustic soda). During the final step, virtually all of the minerals that constitute the kimberlite are rendered soluble except for the diamonds. The resulting residues are then observed microscopically to identify and recover the diamonds.


A mineral of the spinel group. The principle ore of chromium. A kimberlite indicator mineral.


The portion of mining ground held under the federal or local laws by one claimant or association, by virtue of one location and record.


A cylindrical section of rock, usually about an inch in diameter, brought to the surface by diamond drilling for geological examination and/or laboratory analysis.

Crater Facies

Kimberlite material found nearest the top of pipes; preserved only in primary deposits that have undergone little or no erosion since their en-placement.


A portion of the earth’s crust which has been stable for a geologically long period of time. Most diamondiferous kimberlites worldwide are associated with Archean cratons.


A Diamond Is The hardest mineral known, and composed of Pure carbon.

Diamond Stability Field

A region of the earth’s interior between the crust and the core, at depths between 150km and 200km. This is where specific pressure and temperature conditions are favorable for diamond growth and preservation.


Containing Diamonds.

Diatreme Facies

Kimberlite contained within a tapered carrot-shaped sub-volcanic “diatreme” about one kilometer below the earth’s surface.

Dense Media Separation (DMS)

A process by which minerals are separated by utilizing each minerals unique specific gravity. Specific gravity is a relative measurement between the weight of a mineral and water. Some minerals are light and float, while others are heavy and sink. DMS takes advantage of the differences in specific gravity between various minerals as a means to separate one from another.


A tabular body of igneous rock that cuts across the structure of adjacent rocks.


Diamonds are generally either eclogitic or peridotitic. Eclogitic diamonds are found crystalized in ecologitic source rocks. Eclogites are essentially biminerallic rocks composed of pyrope-almandine garnet and omphacitic clinopyroxene.

Em Survey

A method of geophysical surveying which measures a rock’s electromagnetic properties.


Winding ridges of gravel and sand. Left behind by melt-water from a retreating glacier or ice sheet.


The work involved in looking for ore. It may include geologic reconnaissance, e.g. remote sensing, photogeology, geophysical and geochemical methods, and both surface and underground investigations.


A fracture or a zone of fractures in the Earth’s crust, marked by the relative displacement and discontinuity of a layer or layers of rock.


An extensive crack, break, or fracture in rocks.


Pieces of rock or ore which have been separated from a larger, in situ, body of ore by natural forces.

Geochemical Survey

The mapping of geochemical characteristics of a rock.


The science concerned with the study of the Earth, the rocks of which it is composed, and the changes which it has undergone or is undergoing.


The measurement of a rock’s distinct physical properties such as magnetic susceptibility, conductivity and density using specialized measuring devices and computers.

Geophysical Survey

The exploration of an area in which geophysical properties and relationships unique to the area are mapped by one or more geophysical methods. Geophysical techniques are helpful in diamond exploration because Kimberlites often have characteristic geophysical signatures that are unique or distinctive when compared to those of the surrounding rocks.

Glacial Drift

Sediment that is either in transport in glaciers or deposited by glaciers.


A coarseograined rock in which bands rich in granular materials alternate with bands of mainly metamorphic rock.


A light colored, coarse-grained, igneous rock consisting of quartz, alkali feldspar, micas and other associated minerals.


In diamond exploration, the number of carats in a physical unit of ore, usually expressed in carats per ton.

Gravity Survey

Measurements of the gravitational field at a series of different locations. The object of such a survey is to associate variations with differences in the distribution of densities and hence of rock types.

Heavy Mineral

A mineral of sedimentary rock, of high specific gravity.

Heavy Liquid Separation

Separation of ore particles by allowing them to settle through, or float above, a fluid of intermediate density.

Host Rock

A body of rock serving as host for other rocks or for mineral deposits.


A general adjective applied to minor intrusions such as sills and dykes, and to the rocks that compose them. Hypabyssal rocks are those that have risen from the depths as magma but solidified mainly as minor intrusions such as dykes and sills before reaching the surface.

Igneous Rocks

Formed by solidification of hot mobile material termed magma.


The principle ore of titanium. A kimberlite indicator mineral.

Indicator Mineral Train

The area where kimberlite indicator minerals are concentrated is variously described as indicator mineral “train”, “fan”, “dispersion”, or “anomaly”. The “train” was created by glacial ice which carried surface material and dispersed over vast areas. Kimberlites are soft and tend to weather more readily than “older” country rocks. As a result, any kimberlite that lay in the path of a glacier was scoured out, incorporated into the glacial drift and dispersed across the landscape. Kimberlite indicator minerals were similarly dispersed through the same process.


A type of magma which originates very deep within the Earth, and passes through the regions that contains diamonds that have crystallized in mantle host rocks.

Kimberlitic Indicator Minerals

Diamonds, Garnets, and several other minerals which are unique to kimberlitic rocks.


A group name for dark colored hypabyssal or extrusive rocks rich in potassium and magnesium.


A group name applied to dark dyke rocks in which dark minerals occur; sometimes contains diamonds.


Relatively large (0.5mm to 10mm)rounded to anhedral crystals (primarily olivine) set in finer grained matrix.

Macrodiamond / Microdiamond

Diamonds having at least one dimension greater than 0.5mm are often referred to as macrodiamonds. Diamonds with dimensions of less than 0.5mm are often referred to as microdiamonds.


Naturally occurring molten rock.

Magnetic Survey

A geophysical survey that measures the level of a rock’s magnetic field.


The zone of the Earth below the crust and above the core. The mantle is divided into the upper mantle and the lower mantle, with a transition zone in between.

Metamorphic Rocks

Includes all those rocks which have formed in the solid state in response to the pronounced changes of temperature, pressure, and chemical environment, which take place in general, below the Earth’s surface.

Mini-Bulk Sample

The collection and processing of typically one to one hundred tons of kimberlite as part of the initial steps on the road to developing a viable diamond mine.


A naturally formed chemical element or compound having a definite range in chemical composition, and usually having a characteristic crystal form.


An olive-green, grayish-green, or brown orthorhombic mineral. Considered a Kimberlite indicator mineral.


Bedrock or strata projecting through the overlying cover detritus and soil to be exposed at the surface.


Designates material of any nature, consolidated or unconsolidated, that overlies a deposit of useful materials, ore, or coal.


“Piqued 1” Clarity term used by most countries other than the U.S. It’s equivalent in American Terms is I1. I1 Meaning inclusions can be seen by the naked eye.


“Piqued 2” Clarity term used by most countries other than the U.S. It’s equivalent in American Terms is I2. I2 Meaning larger inclusions can be seen by the naked eye.


“Piqued 3” Clarity term used by most countries other than the U.S. It’s equivalent in American Terms is I3. I3 Meaning inclusions are incredibly visible to the naked eye. One step lower and you would have “custom jewelry”

Parcel, Parcels

The paper used to wrap diamonds. Usually for single stones. It has an uncanny way of securing the solitaire diamond in place.


Usually Pave, Paved, and MicroPave engagement rings  refers to the smaller diamonds that are set along side the band or next to the center or main diamonds. Usually with a carat weight of .2. Give or take a .05. Of course the size can vary.

Pegasus Overseas

The company that perfected the high pressure color change in diamonds. Where Enhanced diamonds have glass and various other tools to mask and sharpen the look of diamonds, they can not change the color. Pegasus Overseas changed all that by allowing a person to actually change a drastically yellow diamond into a perfect D colored perfect white diamond. Only sophisticated labs such as De-Beers, GIA, EGL and so forth can actually tell the difference using highly technical machinery.


Nothing is absolutely perfect! If you look hard enough you will find imperfections in a stone. Only you might need a highly magnified lens to see it. However in typical standards, Perfect is described as the color D and clarity of FL. Take a look at Flawless versus Internally Flawless Clarity Grading, as these two diamond grades get interchanged quite often.


The ability of some diamonds, minerals or gems to actually keep emitting light for a period of time after being exposed to sun light , normal light, ultra violet light or any other source. It’s usually a glowing effect after the light source has been removed. Sometimes referred to as Diamond Fluorescence.


One of the rarest colors and often very desirable color of diamond. VERY Expensive.


Tiny inclusions in a gem or diamond.


Usually referred to as a diamond mine.


Weight equally 100th of a carat. So a 1ct diamond would equal 100 points, and a half carat diamond would be 50 points, and so forth. See Diamond Carat Weight.

Polish Lines

Usually faint lines left by careless or accidental polishing. Also could be lines that are just naturally occurring in the diamond itself. Learn more about Diamond Polish. It makes a real difference in a diamond’s overall beauty.

Polish Burn

A mark on a diamond resulting from getting the diamond too hot when polishing it. Usually results in cloudiness.


A diamond substitute very often found in watches. It’s used for it’s remarkable clarity and colorless appearance.


The monthly newsletter invented by Martin Rapaport that is used by the entire diamond industry as a set standard for diamond prices. Another words if the Rapaport says a 1.3ct, G, SI1 round diamond is worth $1000 a carat than you would times 1.3 by 1000 and you would get $1300. This is what Rapaport suggests the selling price usually is. However not everyone follows it.


Retail prices, the kind you find in a lot of websites and local jewelry stores in your nearby mall all markup from the Rapaport price. At times usually 2 times the suggested price of Rapaport. So the $1300 diamond mentioned above could and usually would cost you about $2000 to $2600 in a jewelry store. Simply put Retail is the markup of Rapaport. This is how sales are possible.


The person who’s responsibility is to put, or set, the diamond into the pegs or mount of a ring.


A machine that sorts rough diamonds by size.

SI1 – Slightly Included

The SI1 Clarity term used for diamonds that should NOT show any inclusions visible to the naked eye. However under 10x magnification inclusions will be very visible.


Usually means a ring or other piece of jewelry that has only 1 major diamond mounted in the settings. Usually referred to as an engagement ring. Make note that a solitaire is a term used for defining an engagement band.


If you see a diamond with this clarity than you’re dealing with a diamond that’s absolutely junk. It’s the step below I3. Usually costume jewelry would fall into this category. Only custom jewelry is probably nicer to look at.


Usually one of the most un-talked about properties of a diamond. When in fact it usually is one of the most important. Diamond Symmetry is just as it says, and refers to the equal-ness of all sides of a diamond. The more symmetrical the more light can pass back up through the diamond and give it it’s sparkle or fire.


Diamonds that have been created in a lab. Make note that Synthetic diamonds are in fact VERY REAL diamonds. It’s a complicated process, but the diamond is actually grown in a lab using extreme pressure that mimics the natural forces of nature. However instead of waiting for millions of years for the carbon to turn into a diamond it takes about 3 days to a week in a lab. Usually Synthetic diamonds are much cheaper, and have absolute perfect clarity. De Beers, in a panic, has devised a machine that can tell the difference between good old earth made diamonds, and man made diamonds keeping the value and integrity of diamonds intact. The technology for the synthetic diamond is so good that very few people can see any difference. It does take a machine.

Table Facet

The very top and largest facet on a diamond.


A tool used to hold a diamond while it’s being polished.


The diamonds ability to emit light when heated.

Treated, Treatment

The process of enhancing the color of a diamond or clarity enhancing a diamond outside of it’s normal process of cutting and polishing. Usually done by high pressure to change the color, or by drilling and injecting a glass like material into a diamond to change it’s clarity or appearance. Both are very popular, both are NOT illegal, both designed to enhance the beauty of the diamond.

VS1, VS2, Very slightly included

The clarity of a diamond that indicates that there are absolutely no inclusions visible to the naked eye, and hard to see under 10x magnification. See VS1 vs VS2.

VVS1, VVS2, Very, Very slightly included

The clarity value of a diamond that’s almost near perfect in clarity. Very Very refers to that you can barely see the inclusions even using a 10x magnified lens, and you certainly can not see it with your naked eyes.