Sapphirine Value, Price, and Jewelry Information
Sapphirines are durable but very rare gemstones. Although named after their typically sapphire-blue color, these gems can occur in different hues and display pleochroism, too.
Sapphirine Value
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Sapphirine Information
| Data | Value |
| Name | Sapphirine |
| Crystallography | Monoclinic or triclinic; crystals tabular; usually granular or as disseminated grains. |
| Refractive Index | 1.701-1.723 |
| Colors | Pale blue, bluish gray, greenish gray, green, purplish, brown; depth of blue color varies with Fe. Also, (rarely) purplish pink, red. |
| Luster | Vitreous. |
| Fracture | Uneven to subconchoidal |
| Hardness | 7.5 |
| Specific Gravity | 3.4-3.5 |
| Birefringence | 0.006 |
| Cleavage | Indistinct |
| Dispersion | 0.019 |
| Luminescence | Inert, except for rare red gems. See "Identifying Characteristics" below. |
| Wearability | Very Good |
| Transparency | Translucent to transparent. |
| Absorption Spectrum | Not diagnostic. |
| Formula | Mg3.5Al9.0Si1.5O20 (+Fe). Complex substitution of Mg/Al/Si with charge balancing. Two polytypes:
|
| Pleochroism | Distinct: X = pinkish buff; yellowish; pale smoky brown; colorless: Y = sky blue; sapphire blue; greenish blue; Z = dark sky blue; sapphire blue. |
| Optics | a = 1.714-1.716; β = 1.719-1.721; γ = 1.720-1.723. Biaxial (-). See "Identifying Characteristics" for variations. |
| Etymology | In allusion to the stone’s “sapphire blue” color. |
| Occurrence | In mineral veins or cavities in eruptive igneous rocks. |
Comments
Sapphirine has loaned its name to the sapphirine mineral supergroup, which contains three subgroups, including the sapphirine group.
Even though sapphirines occur in transparent grains, facetable material is exceedingly rare.
Despite its name and most well-known color, sapphirine is a gem species distinct from sapphire. However, like sapphire, it too occurs in more colors than blue, albeit rarely. These colors include shades of violet, purple, green, pink, and brown. In 2007, a red variety was discovered in Tanzania. In addition, sapphirines can show very strong trichroic colors depending on the viewing angle.
“Sapphirine Chalcedony”
The term “sapphirine” has sometimes been applied incorrectly to blue specimens of chalcedony, crystalline quartz, and spinel. One specific usage in art history persists. The gemologist Fred Gray writes that the ancient Greeks created scarab-like seal rings and particularly favored light blue chalcedony. In recent times, this material received the French name of “sapphirine.”
Identifying Characteristics
Sapphirine’s refractive indices (RI) are close to those of idocrase. However, the former has a biaxial negative optic character. (Please note that idocrase may be anomalously biaxial). Sapphirines also exceed idocrase in specific gravity (SG).
An unusual, 1.54-ct, oval-cut, purplish-pink specimen from Sri Lanka (initially reported as idocrase) had the following properties:
- RI = 1.701-1.707 with a β = 1.705.
- Birefringence = 0.006.
- SG = 3.51.
The rare red sapphirine from Tanzania reportedly has the following luminescent properties under ultraviolet light (UV):
- Longwave UV: dull red.
- Shortwave UV: weak orange.
Serendibite, another rare mineral in the sapphirine supergroup, also occurs very rarely in gem-quality condition. Since the 1990s, faceted serendibites have begun to appear on the market. While sapphirines and serendibites may appear very similar and have overlapping properties, sapphirines usually have higher RIs and hardness.
Synthetics
Scientists have synthesized sapphirines for geological research. However, there is no known jewelry use for this material.
Enhancements
No known gem treatments.
Sources
Madagascar and Sri Lanka are the principal producers of gem-quality sapphirines.
Other gem-quality sources include the following:
- United States: Keweenaw Peninsula, Michigan; Lake Superior, Minnesota; Milford, Utah.
- Australia; Canada; Czech Republic; Greenland; Italy; Japan; South Africa; Sweden; Tanzania; Thailand; Scotland, United Kingdom.
Care
With a hardness of 7.5 and poor or indistinct cleavage, sapphirines would make good stones for everyday jewelry wear, especially if you like their classic blue appearance. Although small, most gem-quality stones are generally eye clean. These gemstones require no special care or cleaning methods.
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