Gemology Articles

Spectroscopic and imaging technologies continue to improve.

Myanmar produces many fine rubies from metamorphic deposits.

Responsible mining aims to minimize habitat disruption.

Professional treaters use calibrated furnaces with precise control.

Treated gems often require special handling.

Gemstones are tangible assets whose value depends on quality factors.

Demand continues to grow for fully disclosed, traceable gems.

Laboratory-grown gems have identical properties to natural counterparts.

Reports from GIA, SSEF, Gübelin provide objective documentation.

Untreated stones of equivalent color, clarity, and size command substantial premiums.

The main factors are color, clarity, cut quality, carat weight, and rarity/origin.

Zircon (ZrSiO₄) has high refractive index and strong dispersion.

Pearls form when mollusks secrete layers of nacre around an irritant.

Opal is amorphous hydrated silica (SiO₂·nH₂O).

Garnets form an isomorphous series of silicate minerals.

Quartz (SiO₂) is one of the most abundant minerals.

Tourmaline belongs to a group of boron silicates with wide chemical variation.

Topaz is an aluminum silicate fluoride hydroxide.

Emerald is the green variety of beryl (Be₃Al₂Si₆O₁₈).

Corundum is aluminum oxide (Al₂O₃) with a hexagonal crystal structure.

Diamond consists of carbon atoms in a face-centered cubic lattice.

Modern authentication integrates traditional testing with chemical fingerprinting.

High-magnification microscopy reveals internal features that fingerprint a gem's origin.

Synthetic gems possess the same chemical composition and crystal structure as natural ones.

Absorption spectroscopy reveals which elements or defects cause color.

Standard equipment includes the refractometer, polariscope, dichroscope, and spectroscope.

Natural untreated gems exhibit color and clarity produced solely by geological processes.

International trade organizations and laboratories require full disclosure of any treatment.

Treatment status is a major pricing factor.

Laboratories combine traditional and advanced tools to identify treatments.

Lattice diffusion introduces trace elements into the surface layer of corundum.

Fracture filling injects colorless substances into surface-reaching breaks.

Irradiation bombards gems with gamma rays, neutrons, or electrons to modify color.

Oiling fills surface-reaching fractures in emeralds and other stones.

Heat treatment exposes gems to controlled temperatures to alter color or improve clarity.

Gem treatments are controlled processes that improve a stone's color, clarity, durability, or appearance.

Cut quality can account for 20–40% of a colored gem's value.

Small artisanal workshops emphasize custom, high-precision work on valuable rough.

Faceting machines allow cutters to place facets at exact angles calculated from a gem's refractive index.

Cabochon cutting produces a smooth, polished dome with a flat or slightly convex base.

Common faceted shapes include round, oval, cushion, emerald, pear, marquise, and princess.

Brilliant cuts use triangular and kite-shaped facets arranged to maximize light return.

Lapidary involves sawing, grinding, faceting, and polishing rough gem material into finished stones.

Primary deposits contain gems still embedded in the host rock where they crystallized.

Gemstones crystallize through igneous, metamorphic, hydrothermal, or sedimentary processes.

Inclusions are internal features formed during or after a gem's crystallization.

Specific gravity (SG), or relative density, is the weight of a gem compared to an equal volume of water.

Refractive index (RI) quantifies how much light slows and bends when entering a gem from air.

The Mohs scale ranks ten minerals from 1 (talc) to 10 (diamond) according to their relative ability to scratch one another.

Gemology is the scientific discipline within mineralogy that focuses on the identification, grading, and evaluation of natural and synthetic gem materials.