achromatic As above
adularescence A phenomenal effect; e.g., the billowing "moonglow" effect in moonstone.
akoya pearl A pearl from the saltwater akoya-gai oyster (Pinctada martensii); "Japanese pearl." ...
achromatic lens One of three lenses in a triplet loupe for the purpose of correcting the chromatic aberration. See chromatic aberration.
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Achromatic colors:
Describes color combinations that are made by neutrals, the ochers, grays and browns. They have a low saturation/value and therefor also have a low degree of hue.
15. Achromatic schemes use no colour, just shades of grey, black and white (also known as grayscale)
Mood Colours
In addition to illustrating how colours can be combined the colour wheel also groups colours into warm and cool colours.
The richness of a color, or the degree to which a color varies from achromaticity (white and black are the two achromatic colors, each totally lacking in hue). When dealing with gems of the same basic hue position (i.e.
The jeweller's loupe has to be tested for achromatic and spherical aberrations. Chromatic aberration refers to colour fringes of the image due to dispersion caused inside the glass lens.
The achromatic loupe consists of two lenses of unequal power and opposite curvature, collecting light of all wavelengths at one focal point and thus avoided achromatic aberration.
A mid 19th-century innovation was the achromatic lens which cut out colour distortions. However, the real breakthrough came when Carl Zeiss marketed prism binoculars in the 1890s.
French word for magnifying glass, universally applied to the version used by most jewellery professionals, with a 10X magnification, although other powers are used. Diamond loupes are normally high quality, colour corrected (achromatic).
Loupe Clean ...
perceptions that by definition cannot be pure spectral colors due to desaturation or because they are purples (mixtures of red and violet light, from opposite ends of the spectrum). Some examples of necessarily non-spectral colors are the achromatic ...
 See also: Surface, Rough, Color, Eye, Inclusions
  
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