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Thursday, 13 August 2020

Gemmology — gemstones — characteristics, classification, specimens, library


characteristics, classification, specimens, library

As gemstones we accept cut specimens of crystals of natural mineral species having a visible transparency and certain durability. From over 4800 known minerals (according to data of the International Mineralogical Association), approximately 150 satisfy the above conditions and form crystals of sufficient size to be cut.

The section ‘Classification’ presents descriptions of 171 different kinds of natural gemstones (106 mineral species). The Nickel-Strunz systematic order (10th edition) is used. Since gemmology does not always follow the systematics of minerals in naming, many popular varieties or just ’names’ are listed.

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— In granite and alkalic granite pegmatites (Anthony et al., 2001—2005). Faceted specimens are extremely rare.

The section ‘Repository’ contains data and photos of 760 specimens of gemstones. The smallest is just 1.96 mm (0.02 ct) ruby from Mozambique, and the largest — 70.11 mm (326.60 ct) rock crystal from Africa. Besides there are 8 specimens of synthetic stones.

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Opal — specimen 0376

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Topaz — specimen 0253
Marialite-meionite series — specimen 0255
Sapphire — specimen 0263
Malaia garnet — specimen 0268

— More from ‘Repository

Currently there are 283 bibliographical references and abstracts to publications with gemmological or mineralogical thematics in the ‘Library’. The section comprises also a glossary with 391 terms.

dike — a sheet of rock that formed in a crack in a pre-existing rock body
diopside — species of mineral; see diopside in ‘Classification’
dodecagon — rare shape in faceting a gemstone
dolomite — species of mineral; see dolomite in ‘Classification’

Klaproth, M. H., 1802 — Chemische Untersuchung des Gadolinits — Published in 1802 in ‘Beiträge zur Chemischen Kenntniss der Mineralkörper’; contains the original description of the mineral gadolinite-(Y).
Kenngott, A., 1853 — Hemimorphit — Published in 1853 in ‘Das Mohs’sche Mineralsystem’; contains the original description of the mineral hemimorphite.