A little-known gem material of truly exquisite color, sky-blue ceruleite takes a very high polish easily and quickly. However, fine, solid, cuttable pieces are extremely rare.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Usually massive, compact, earthy.|
|Colors||Turquoise-blue shades, cerulean blue.|
|Specific Gravity||2.7 – 2.8|
|Transparency||Translucent to opaque.|
|Optics||Mean index ~ 1.60. Very fine grained.|
|Etymology||From the Latin caerulea for “sky blue,” in allusion to its color.|
|Occurrence||Sedimentary material formed in the vicinity of copper deposits, like turquoise.|
Polished ceruleite gems can have a far deeper blue color than that of the rough nodules. Due to its rarity, good, cuttable material is quite expensive. You’ll see few cut stones, even in museum collections.
Ceruleite’s porosity poses a major problem for jewelry use. It renders the material too soft and fragile for cutting and wear. Plastic impregnation can solve this problem. Such impregnated material has a specific gravity of 2.58.
The type locality for this gem is the Emma Luisa Mine in Huanaco, Chile. Chile remains an important source for this gem.
Southern Bolivia has produced cabbing material of fine color. However, the total amount of this yield may not exceed several hundred pounds.
Other notable gem sources include:
- United States: Arizona; Idaho.
- Cornwall, England.
- Australia; France; Namibia; South Africa.
Nodules usually range in size from less than 1 inch up to several inches. Typically small, this material yields cabochons only.
You’re more likely to find ceruleites, if at all, in mineral collections than in jewelry collections. These gemstones have a lower hardness (5-6) than more common jewelry stones such as quartz. Therefore, store them separately from other gems to avoid contact scratches. Use protective settings for ring wear. However, necklace and earring use should pose fewer risks.
Avoid cleaning ceruleites with any mechanical systems. Clean these gems only with a soft brush, mild detergent, and warm water. Don’t use any other cleaning solutions, since ceruleites may react to chemicals in them. Wipe pieces with a damp cloth after wearing them. Consult our gemstone jewelry cleaning guide for more recommendations.