Gemmology
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Wednesday, 28 October 2020


Gemmology — gemstones — characteristics, classification, specimens, library
Amethyst

GEMMOLOGY — GEMSTONES

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.
Characteristics

Colour in gemstones
Clarity in gemstones
Cut in gemstones

Treatment in gemstones

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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List of minerals
Alphabetic list of gemstones
Synthetic stones and simulants
Classification
Featured

Cerussite

— Common in the oxidised zone of lead deposits, where it may constitute an important ore (Anthony et al., 2001—2005). Faceted specimens are very rare. The largest faceted stone is a 408 carat from Tsumeb, Namibia (Arem, 1987: 64).
Cerussite
Clinozoisite
Clinozoisite
Kornerupine
Kornerupine
Serendibite
Serendibite
Vlasovite
Vlasovite

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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Simple colour schemeredorangey redreddish orangeorangeorangey yellowyellowgreenish yellowyellowish greenslightly yellowish greengreenvery slightly bluish greenbluish greenvery strongly bluish greengreen-blue or blue-greenvery strongly greenish bluevery slightly greenish bluebluevioletish bluebluish violetvioletbluish purplepurplereddish purplestrongly purplish redslightly purplish redcolourlessgreyblack
Repository
Obsidian — specimen 0742

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Ruby — specimen 0318
Agate — specimen 0321
Agate — specimen 0322
Agate — specimen 0325

— 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.
Library
Glossary

cobaltite — species of mineral; faceted specimens reported (Iverson, 2012)
cobaltoan smithsonite — variety of smithsonite; see cobaltoan smithsonite in ‘Classification’
coffin — rare shape in faceting a gemstone
colemanite — species of mineral; faceted specimens exist
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Johachidolite — Features the data of johachidolite; from ‘Handbook of Mineralogy’.
Brögger, W. C., 1890 — Die Mineralien der Syenitpegmatitgänge der südnorwegischen Augit- und Nephelinsyenite, 16. Hambergit — Published in 1890 in ‘Zeitschrift für Kristallographie’; contains the original description of the mineral hambergite.


Gemmology — gemstones
Front page | Introduction | Classification | Repository | Library

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The specimens illustrated in this site do not exist in the collections of the National Museum of Natural History, Sofia.