Glass

Q: What is Glass?

Natural and man-made glass, while not a mineral, has been used as a gem material for thousands of years, valued for its ability to be formed in any color, shaped with precision, and polished to a high luster. Volcanic obsidian and tektites such as moldavite and Libyan desert glass are natural geolog

Q: What is the hardness of Glass?

Glass has a Mohs hardness of 4.0 to 6.0, making it relatively soft for use in jewelry.

Q: How much does Glass cost?

Glass falls into the Budget (< $50/ct) price range. Prices vary based on color, clarity, cut, and origin.

Q: What is the crystal system of Glass?

Glass belongs to the Amorphous crystal system.

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Physical & Optical Properties

Category Semi-Precious Gems

Mohs Hardness 4.0 – 6.0

Specific Gravity 2.39 – 4.0

Refractive Index 1.48 – 1.7

Crystal System Amorphous

Luster Vitreous

Fracture Conchoidal

Color various

Mohs Hardness

Mohs Hardness: 4.0 – 6.0

1 Soft10 Hard

Crystal System

Value & Market

Price Tier Budget (< $50/ct)

Where to Buy Glass

Blue Nile Fine jewelry retailer

James Allen Gemstone jewelry

Brilliant Earth Ethically sourced gems

Amazon Wide selection

Links may earn a commission at no extra cost to you.

Treatments

Can be coated with metal foils - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 2 4 to 6Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references 2.39 to 4.00Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references ConchoidalGemdat.org, Management Team (2012) 1.48 to 1.70Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references IsotropicUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Various, play of colourUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references Yellowish green, Fe2+ in octahedral coordination. Brown Fe3+ in octahedral coordinationW. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) Transparent,Translucent,OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references VitreousGemdat.org, Management Team (2012) Strong chalky fluorescence commonHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) AmorphousHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Gas bubbles, swirl marks, partly tabby extinction - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 2 Glass information at mindat.org

About Glass

Natural and man-made glass, while not a mineral, has been used as a gem material for thousands of years, valued for its ability to be formed in any color, shaped with precision, and polished to a high luster. Volcanic obsidian and tektites such as moldavite and Libyan desert glass are natural geological glasses prized as gemstones, while synthetic glass paste gems have been crafted since ancient Egypt and Rome. Glass occupies an important place in gem history as both an affordable ornamental material and a source of remarkable geological specimens.