Term
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Definition
| the range of electromagnetic radiation wavelengths from the longest, low frequency radio waves, through diminishing wavelengths to infrared, visible light, ultraviolet, x-rays and gamma rays, to the shortest of all, very high-frequency cosmic rays (the highest energy waves) |
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Term
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Definition
| electrmagnetic radiations have wavelengths shorter than those of x-rays but longer than those of cosmic rays |
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Term
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Definition
very short electromagnetic radiations (10-10m)
enable various types of pearls to be distinguished; they may cause fluorescence in materials; may be used to artificially change the color of certain gem materials |
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Term
| Ultraviolet (UV) Radiation |
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Definition
electromagnetic radiation with wavelengths just shorter than the visible violet
produces fluorescent effects in some materials, which may be an aid to identification or detection
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Term
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Definition
wavelengths of the electromagnetic spectrum shorter than radio waves but longer than wavelengths of visible light
used in reflectance meters as an aid to identification of gemstones |
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Term
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Definition
| describes the emission of 'cold', non-incandescent, visible light by a substance, as a result of inicident radiation |
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Term
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Definition
| the general term used to describe the emission of visible light by a substance whilst it is being illuminated by radiation of shorter wavelengths (higher energy) |
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Term
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Definition
| a luminous afterglow which persists in some fluorescent materials after the original source of exciting radiation has been shut off |
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Term
| Long Wave Ultraviolet (LWUV) |
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Definition
| a type of ultraviolet light with a principal wavelength of 365nm |
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Term
| Short Wave Ultraviolet (SWUV) |
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Definition
| a type of ultraviolet light with a principal wavelength of 254nm; more dangerous than SWUV |
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Term
| X-Ray Fluorescence Spectrometers (XRF) |
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Definition
| special types of spectrometers that analyze the x-rays re-emitted by a material when excited by x-rays and, from this, detect the presence and concentration of chemical elements in the specimen |
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Term
| Scanning Electron Microscope (SEM) |
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Definition
| an electron beam is scanned across the material and an extremely detailed and highly magnified image can be generated from the scattered electron reflections |
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Term
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Definition
measure absorption in materials through the infrared part of the electromagnetic spectrum
useful in distinguishing natural from flux-melt synthetic emeralds and in detecting the presence of synthetic resins |
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Term
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Definition
a small, portable instrument used for detecting the reflecting power of a surface
employs a light source and the amount of this light reflected by the surface of a gemstone is detected and measured to indicate the relative reflecting power of that surface |
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Term
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Definition
| measures the detectable shift and its signature that occurs when a very strong beam of energy is absorbed by a substance and a tiny amount of energy is re-emitted at a different energy level |
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Term
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Definition
| uses an electron beam - 'cathode rays' - to stimulate visible light fluorescence |
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Term
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Definition
| a measure of the ability of a material to transfer heat |
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Term
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Definition
| describes the rate of heat transfer through a material |
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Term
| Thermal Conductance Probe |
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Definition
| a small, portable instrument designed principally to distinguish diamond from its simulants |
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