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Orange 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） |
Saturated mandarin-orange (cadmium sulfoselenide), tomato-red-orange (selenium-sulfur), pale peach (cerium oxide), warm honey-orange (neodymium oxide), and the rare Murano 'avventurina orange' copper-spangled gold-orange. Cadmium-doped material closely approximates spessartine 'mandarin garnet' from Namibian Kunene or Tanzanian Loliondo deposits.
- 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
- Cadmium-selenide color zoning streaks (schlieren) from incomplete batch mixing
- Devitrification crystallites in older or heat-stressed material
- Murano avventurina orange: metallic copper crystallites visible at 10× as sparkling reflective spangles
- 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
- Mohs 5–6 — easily scratched by quartz (Mohs 7)
- Conchoidal fracture
- Chelsea filter: cadmium-orange glass typically shows weak red-orange response
- 01Regular round gas bubbles visible at 10× — immediately diagnose pressed or molded glass
- 02Singly refractive (no ) — same as natural spessartine garnet (also singly refractive cubic), so polariscope is non-diagnostic for this pair
- 03Refractometer reads 1.50–1.70 versus natural spessartine 1.79–1.81 — clean diagnostic separation
- 04Specific gravity 2.4–4.5 versus natural spessartine 4.12–4.20 — hand-heft gives diagnostic difference at 1 ct and above
- 05Mohs 5–6 scratches against a steel knife; natural spessartine (Mohs 7–7.5) is unaffected
- 06nclusions and growth zoning; glass: regular round bubbles only
- 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
- Cadmium-bearing material: handle as restricted under REACH; avoid prolonged skin contact and pediatric exposure
Modern molded and faceted orange-glass cabochons trade at $0.30–$3 per piece wholesale (Indian and Chinese mass production); Czech Gablonzer pressed-glass material runs $2–$20 per piece. Murano avventurina orange lampwork beads reach $50–$300 per bead at gallery prices. Genuine eighteenth- and nineteenth-century selenium-orange paste (Strass-tradition French, Bohemian Gablonzer) trades at $150–$2,500 per piece at vintage and estate auctions.
Note: Disclosure as 'glass' or 'imitation spessartine/fire opal/Padparadscha' is mandatory under FTC Jewelry Guides §23.25 and CIBJO Blue Book. EU REACH Annex XVII Entry 23 restricts cadmium-bearing glass for consumer jewelry below 0.01 wt% cadmium in the finished article — driving a shift toward selenium and rare-earth alternatives in European production. Beware of cadmium-rich orange glass from non-REACH-compliant sources (some Asian mass production) for children's jewelry and pacifier-clip applications. Murano avventurina orange retains collector value as a documented Italian glass-art tradition. Czech Gablonzer pressed-glass orange cabochons from documented pre-WWII production retain collector value in the antique trade.
Orange glass is amorphous SiO₂-based paste colored orange by various combinations of cadmium sulfoselenide (CdS·CdSe in solid solution, the 'cadmium selenide' or 'cadmium red/orange' colorant system commercialized at Schott Jenaer Glaswerke in 1890), selenium and sulfur (the 'selenium ruby' tradition for the deepest orange-red shades), or rare-earth oxides (cerium oxide CeO₂ for pale orange, neodymium oxide Nd₂O₃ for selective amber-orange). Non-crystalline, isotropic, Mohs 5–6, SG 2.4–4.5, RI 1.50–1.70, singly refractive, conchoidal fracture. The cadmium-selenide system produces the saturated orange-to-red colors that closely approximate spessartine garnet (Manganese-aluminum garnet, the 'mandarin orange' or 'fanta orange' modern trade name introduced for Namibian Kunene production from 1991) and Mexican fire opal saturation. Murano 'avventurina orange' (sometimes 'aventurine glass,' though the modern term is generally reserved for the goldstone variety) uses metallic copper crystallites suspended in soda-lime glass to produce the warm orange tone with characteristic sparkle. Industrial production from Bohemian Gablonzer (Jablonec nad Nisou), Murano (Venice), and modern Indian and Chinese factories.
Origins
abochons. Italy (Murano, Venice — Cima, Salviati, Effetre) supplies lampwork beads in cadmium-orange and the specialty avventurina orange. Germany (Schott Jenaer Glaswerke, Jena, founded 1884 by Otto Schott and Carl Zeiss) is the historical centre for cadmium-selenide colorant chemistry. France (Saint-Gobain, Baccarat) produced eighteenth- and nineteenth-century selenium-and-sulfur orange paste. India (Firozabad) and China (Shandong, Hebei) dominate modern mass production. The cadmium colorants have been restricted under EU REACH regulations since 2010 (Annex XVII Entry 23) for consumer applications, driving a shift toward selenium and rare-earth alternatives in European production.
History
Roman orange glass appears at Pompeii and Herculaneum from the first century CE, using copper-and-iron oxidation in soda-lime base. Pliny's Naturalis Historia Book 36 (c. 77 CE) describes the 'tawny' and 'flame-coloured' glass tones. The Venetian Murano tradition (Angelo Barovier, c. 1450) established medieval European leaded-glass production with orange specialties for ecclesiastical and decorative use. Georg Friedrich Strass's Paris atelier (1730s) introduced selenium-and-sulfur 'jacinth paste' as imitations of hyacinth zircon and hessonite garnet. The systematic development of cadmium-sulfoselenide pigments at Schott Jenaer Glaswerke under Otto Schott from the 1890s — building on Friedrich Stromeyer's 1817 isolation of cadmium at the University of Göttingen and Jöns Jakob Berzelius's 1817 discovery of selenium at Karolinska Institutet — revolutionized orange-glass production by providing stable, brilliant colorants that survived the high-temperature glass-melting process. The Bohemian Gablonzer pressed-glass works adopted the cadmium-selenide system from the 1900s. Daniel Swarovski's 1892 Wattens factory and Coco Chanel's 1920s costume-jewelry collections incorporated orange paste alongside crystal and other colors. The 1968 US FTC Jewelry Guides §23.25 required explicit 'glass' or 'imitation' disclosure, and the 2010 EU REACH restrictions on cadmium have constrained European production.
Lore & symbolism
No birthstone designation (synthetic/imitation material). Spessartine garnet — the natural species most often imitated by orange glass — was originally named in 1832 by Carl Friedrich Christian Mohs (the originator of the scale) for the Spessart Mountains in Bavaria, Germany; the modern 'mandarin garnet' trade name was introduced by Werner Spaltenstein for Namibian Kunene production from 1991. The Bohemian Gablonzer regional craft tradition is preserved under UNESCO intangible cultural heritage. Modern crystal-writing assigns no specific spiritual properties to glass imitations.
Tools to confirm this stone
Tools that help confirm Orange 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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