Gemmology
English | Български
Thursday, 17 January 2019


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

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.

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.

Quick navigation selector

Classification
Featured

Sanidine

— Most common in felsic volcanic rocks; in volcanic glass; also from mafic, high-temperature contact metamorphic, and hydrothermally altered rocks; from eclogite nodules in kimberlite (Anthony et al., 2001—2005).
Sanidine

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.

Gallery view selector

Colour selector
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
Melanite — specimen 0645

Some exceptional specimens of gemstones from our ‘Repository’

More specimens of gemstones
Carnelian — specimen 0010
Titanite — specimen 0016
Carnelian — specimen 0020
Carnelian — specimen 0021

— 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

phonolite — a rare extrusive igneous rock, of intermediate chemical composition between felsic and mafic
phosphophyllite — species of mineral; faceted specimens exist
phosphosiderite — species of mineral; see phosphosiderite in ‘Classification’
pleochroism — оn optical phenomenon in which the gemstone appears to be different colours when observed at different angles
Publications

Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Bromellite — Features the data of bromellite; from ‘Handbook of Mineralogy’.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (Eds), 2001—2005 — Cuprite — Features the data of cuprite; from ‘Handbook of Mineralogy’.