Gemological Terms, Tools, & Properties

Adamantine Luster
Adamantine is the term used to describe the luster exhibited by diamonds and gems with a Refractive Index of 1.9 - 2.5. The root word adamant ...
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Adularescence
Adularescence is an optical phenomena often called the “moonstone” effect. The phenomenon is applied to feldspar, usually orthoclase that, when ...
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Alexandrite-Like
Alexandrite-like refers to the ability of a gem material to change colors when viewed under different light sources such as daylight and ...
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Allochromatic
The term allochromatic is used in reference to gem materials that derive their color from elements that are not an ...
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Aventurescence
Aventurescence is a phenomenon in gemstones whereby glittering reflections of small inclusions of hematite or goethite in feldspar or fuchsite ...
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Birefringence
Birefringence is the strength of double refraction as measured by computing the difference between the high and low indices of a ...
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Body Color
Body color refers to a pearl's overall color. White, cream, pink and black are the most commonly seen body colors. The ...
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Brilliance
Brilliance is a term used to quantify the brightness of a gemstone. Brightness, and therefore brilliance, are related to the surface ...
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Calcareous Concretion
Calcareous concretions are pearl-like growths produced in mollusks that lack nacre. While still composed of calcite and aragonite, the crystals are much coarser. Some ...
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Change of Color
A phenomenon of some colored gemstones in which the gem material appears a different color in incandescent light than in daylight ...
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Chatoyancy
An optical phenomenon which appears as a bright band of light across certain gemstones that when cut as cabochons, reproduce ...
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Colored Stone
Colored stones are all gemstones that are not a diamond. The term is used as a general catch-all for gemstones.Georgian Style ...
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Composite Stone
Composite Stone - Triplet. Composite stones are gem simulants that are composed out of several materials. Doublets and triplets are good examples. Composite stones ...
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Crown-Gemstone
Crown, Girdle, Pavilion.The crown of a gemstone refers to the part above the girdle ...
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Cryptocrystalline
Having crystals so small that individual crystals cannot be seen under ordinary optical microscope, but are detectable by effect under ...
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Crystalline
A crystalline material is a substance with a regular, repeating, 3-dimensional atomic structure. We divide crystalline materials into monocrystalline and ...
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Diaphaneity
Diaphaneity is the general term to describe the transmittance of light through an object. The three typical classifications are transparency, translucency, and opacity ...
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Dichroscope
A small gemological instrument that is used to detect pleochroism in a material. Using either a calcite crystal or polarizing ...
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Dispersion
Synthetic Rutile Showing a High Amount of Dispersion. Image Courtesy of Jeffrey HuntThe separation of white light into the component ...
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Double Refraction
The property of splitting a single beam of light into two polarized beams which pass through a crystal at different ...
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Dull Luster
Dull luster describes the luster of Ivory. Japanese Shibayama Ivory Box with Dull Luster ...
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Durability
Durability refers to a quality of gemstones to withstand wear and tear in normal use. It depends on hardness (the ...
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Enhancement
Laser Drilled Diamond. The Visible Drill Channels are Not All Individual Channels, for the Most Part, They are Reflections.Image Courtesy ...
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Fluorescence
The emission of visible light by a material, such as a diamond, when illuminated by ultra-violet light or X-radiation. A ...
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Gem Phenomena
Gem phenomena, or optical phenomena, are the observable characteristics of gemstones, such as asterism, play-of-color and chatoyancy. Phenomena are usually a result of light interacting ...
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Gota de Aceita
In addition to the streamlined geometric styling, fine Art Deco jewels of the 1920s-30s are noted for their superior gemstones and here we have ...
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Greasy Luster
Greasy is the term used for the surface reflection on materials as seen on Serpentine. Serpentine Paten with Gold Inlay ...
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