Danburite Value, Price, and Jewelry Information
A very durable gemstone, danburite is an excellent choice for jewelry use. Although the mineral isn't rare, large facetable pieces are scarce. Still, sufficient material exists for gem enthusiasts and adventurous jewelry lovers to add this lovely and underappreciated stone to their collections.
Danburite Value
Tried and true gem value factors apply to danburite. All other things being equal, larger, cleaner, better cut and better colored stones have a higher value per carat. However, a truly colorless specimen would surpass a very pale yellow or slightly pink stone in value per carat.
Princess-cut colorless 8.65-ct danburite, 12.26 mm, Russia. © Kosnar Gem Co. Used with permission.
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Danburite Information
| Data | Value |
| Name | Danburite |
| Crystallography | Orthorhombic; Crystals prismatic with wedge-shaped terminations, like topaz. |
| Refractive Index | 1.627 - 1.641 |
| Colors | Colorless, white, pink, light to dark yellow, yellowish brown, brown, blue. |
| Luster | Vitreous to greasy. |
| Fracture | Subconchoidal to uneven |
| Hardness | 7 |
| Specific Gravity | 2.97-3.03, usually 3.00. |
| Birefringence | 0.008-0.009 |
| Cleavage | Indistinct |
| Dispersion | 0.017 |
| Luminescence | Sky blue to bright blue-green in LW. Also, thermoluminescent (red). |
| Wearability | Excellent |
| Transparency | Transparent. |
| Absorption Spectrum | Sometimes shows rare earth spectrum, so-called didymium lines. |
| Phenomena | Chatoyancy (rare). |
| Formula | CaB2Si2O8 |
| Pleochroism | Weak: pale-yellow/yellow. |
| Optics | a = 1.627-1.633; β = 1.633-1.637; γ = 1.636-1.641. Biaxial (-); 2V= 88° in red to green light; optically (+) at lower wavelengths. |
| Etymology | After the type locality, Danbury, Connecticut. |
| Occurrence | In dolomites; in carbonate veins in granitic rocks. |
| Inclusions | Fingerprints (healed fractures), hollow growth tubes. |
Comments
Danburite’s colors typically range from colorless to light yellow, pale pink, or tan. With poor cleavage and a hardness of 7, it ranks with popular jewelry stones such as quartz and topaz in toughness. Although its modest dispersion means cut danburites lack fire, properly cut gems are very bright. Rare specimens may also display chatoyancy.
Identifying Characteristics
Interestingly, most specimens fluoresce a sky blue color in longwave ultraviolet light and phosphoresce red when heated.
Synthetics
Laboratories have synthesized danburite for research into phosphorescence. However, there’s no known jewelry use for this material.
Enhancements
No known gem treatments.
Sources
First discovered in Danbury, Connecticut, gem-quality danburite has since been found in many locations. Other notable sources include the following:
- Japan: Obira, Bungo, Kyushu, colorless crystals, sometimes gemmy.
- Madagascar: yellow crystals at Mt. Bity, often gemmy.
- Mexico: Charcas, San Luis Potosí, colorless, yellow, light pink (gemmy).
- Myanmar: Mogok, yellow and colorless, sometimes large crystals (rolled pebbles).
- Russia: colorless, gemmy material.
- Bolivia; China; Tanzania; Vietnam.
Stones Sizes
Danburites, especially colorless material from Mexico, typically range in size between 1 and 5 carats. Yellow gems from Myanmar between 7 and 10 carats are very rare.
- British Museum of Natural History (London): Myanmar, wine-yellow, step-cut, flawless, 135.61.
- Smithsonian Institution (Washington, D.C): 18.4 (Myanmar, yellow) 12.4; 10.5 (Mexico, colorless); 7.9 (Japan, colorless).
- Los Angeles County Museum (Los Angeles): Madagascar, brownish, emerald cut, 115.
- Royal Ontario Museum (Toronto, Canada): Russia, colorless, step-cut, 12.72.
- Private Collections: 20 (Myanmar, peach color); 22.76 (Madagascar, yellow); 37 (Russia).
Care
Due to some heat sensitivity, avoid steam cleaning this gem. Otherwise, danburite requires no special care. You can use these gems for all jewelry applications, including rings and bracelets. Consult our gemstone jewelry cleaning guide for more care recommendations.
