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Brown Glass
| Hardness | 5-6 |
| Specific gravity | 2.3-4.5 |
| Refractive index | 1.44-1.70 |
| Crystal system | 非晶質（アモルファス） |
Honey-amber, cognac, chocolate-brown, smoky-grey-brown, and the rare 'tortoiseshell paste' striated brown-and-amber traditional Bohemian variation. Iron-only batches yield greenish brown; iron-plus-manganese yields cleaner neutral brown; iron-plus-sulfur yields the warmest amber-honey tones. Jewelry-grade brown glass is calibrated to imitate citrine (yellow-brown), smoky quartz (cool brown), and natural amber (warm honey) tones.
- Regular round gas bubbles distributed evenly through the matrix — diagnostic of pressed or molded glass at 10×
- Surface molding seams and press-die parting lines on backs
- Iron-rich color zoning streaks (schlieren) from incomplete batch mixing
- Devitrification crystallites in older or heat-stressed material
- Lampwork beads: spiral flow lines from molten-glass winding
- Singly refractive (amorphous glass structure) — no
- Refractive index 1.50–1.70 depending on lead content
- Specific gravity 2.4–4.5 — lead-crystal at the high end, soda-lime at 2.4–2.5
- Mohs 5–6 — easily scratched by quartz (Mohs 7)
- Conchoidal fracture — diagnostic of amorphous materials
- 01Regular round gas bubbles visible at 10× — immediately diagnose pressed or molded glass
- 02Singly refractive (no ) versus natural smoky quartz's clear at 30× immersion
- 03Refractometer reads 1.50–1.70 versus smoky quartz 1.544–1.553 (overlapping but diagnostic when combined with bubble examination)
- 04Mohs 5–6 scratches against a steel knife; natural smoky quartz (Mohs 7) is unaffected
- 05Natural amber: SG 1.05–1.10 floats in saturated salt water (10% NaCl); brown glass at SG 2.4–4.5 sinks immediately — diagnostic single-test separation
- 06Natural amber under SW-UV: characteristic bluish-white ; brown glass: generally inert
- Mohs 5–6 — stores separately to avoid scratches
- Avoid ultrasonic cleaning — vibration can crack the brittle matrix
- Stable to light and mild detergent; warm soapy water and soft brush
- Avoid thermal shock — conchoidal fracture risk
- Avoid strong acids and bases — surface etching possible
Modern molded and faceted brown-glass cabochons trade at $0.20–$3 per piece wholesale (Indian and Chinese mass production); Czech Gablonzer pressed-glass material runs $1–$20 per piece. Murano lampwork brown beads in tortoiseshell paste or millefiori techniques reach $30–$200 per bead at gallery prices. Genuine eighteenth- and nineteenth-century amber paste (Strass-tradition French, Bohemian Gablonzer) trades at $150–$2,500 per piece at vintage and estate auctions.
Note: Disclosure as 'glass' or 'imitation amber/citrine/smoky quartz' is mandatory under FTC Jewelry Guides §23.25, CIBJO Blue Book, and JIS Z 9529. Beware of brown glass marketed as 'pressed amber' or 'reconstituted amber' — true reconstituted amber (Polybern, ambroid) is heat-pressed natural amber chips at 200–250°C and 5,000–10,000 psi and contains identifiable natural amber fragments under polarized light, whereas glass imitations show the characteristic round gas bubbles. Czech Gablonzer pressed-glass brown cabochons from documented pre-WWII production retain collector value in the antique-costume-jewelry trade. Modern Swarovski-style brown crystal components dominate the autumn-themed and seasonal costume-jewelry markets at $0.30–$5 per piece wholesale.
aceting and cutting. Industrial production is dominated by Bohemian Gablonzer (Jablonec nad Nisou, Czech Republic), Murano (Venice, Italy), Indian Firozabad, and Chinese Shandong/Hebei factories.
Origins
aceted stones, in continuous production since the 1820s. Italy (Murano, Venice) supplies lampwork beads using iron-manganese colorant systems in soda-lime glass. France (Saint-Gobain, Baccarat) produced eighteenth- and nineteenth-century 'amber paste' descended from Strass tradition. Germany (Lauscha, Thuringian Forest) is the historical centre for lampwork bead-making. India (Firozabad, Uttar Pradesh) and China (Shandong, Hebei provinces) dominate twentieth- and twenty-first-century mass production. The Stourbridge (West Midlands, England) and Bristol works contributed the British 'amber glass' trade tradition through the nineteenth century.
History
abochons specifically as substitutes for natural tortoiseshell (Hawksbill shell, prohibited under CITES Appendix I since 1977) and natural amber. Daniel Swarovski's 1892 Wattens factory founding and the 1908 Aurora Borealis coating revolution extended brown-paste production into modern costume jewelry; Coco Chanel's 1920s costume-jewelry collections featured extensive use of brown and amber paste alongside black jet and crystal paste. The 1968 US FTC Jewelry Guides §23.25 required explicit 'glass' or 'imitation amber/citrine' disclosure in trade.
Lore & symbolism
No birthstone designation (synthetic/imitation material). The amber-paste tradition carries the cultural associations of natural amber — solar warmth, preservation, Baltic trade history, and the Greek 'electron' (ἤλεκτρον) etymology that gave both amber and electricity their names. Pliny's Naturalis Historia Book 37 (c. 77 CE) records the Roman amber trade and the substitution of amber paste for natural Baltic amber when supplies were short. The Bohemian Gablonzer regional craft tradition is preserved under UNESCO intangible cultural heritage protection. Modern crystal-writing assigns no specific spiritual properties to glass imitations.
Tools to confirm this stone
Tools that help confirm Brown Glass. Tap any item to jump to the matching section on the gem tools page.
- 最終確認日
- 2026年4月28日
- 参 考 文 献
- Gem Encyclopedia／ GIA (Gemological Institute of America)
- 宝石鑑別基準／ 中央宝石研究所 (CGL)
- Mineral & Gem Database／ Mindat.org / Gemdat.org
- 宝石学入門／ 全国宝石学協会
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