Friday, 30 October 2026

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).

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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Repository

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones

— 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

tektite — natural glass; see tektite in ‘Classification’

tenebrescence — the ability of minerals to change colour when exposed to sunlight

tetrahedrite — species of mineral; faceted specimens exist

thaumasite — species of mineral; faceted specimens exist

Publications

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.

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.