Vivianite is so fragile and soft, any faceted gems would be difficult to handle safely, let alone wear. Nevertheless, its blue and green colors are so rich, a few stones (very few) have been cut. Vivianites make beautiful collector’s gemstones.
Color darkens in light.
Fe3(PO4)2 · 8H2O.
After J. H. Vivian, the English mineralogist who discovered the species.
A secondary mineral in ore veins. Also occurs as an alteration product of primary phosphate minerals in granite pegmatites; forms as sedimentary concretions.
In an interview, rare gem faceter and supplier C. D. Parsons acknowledges looking forward to cutting vivianite someday, something very few have done. With a hardness between talc and gypsum and perfect cleavage, few could facet this stone. Thin pieces are even flexible and sectile (cuttable with a knife).
However, this gem material can show beautiful dark shades of blue and green. It also displays intense pleochroism. Depending on the viewing angle, stones can reveal up to three colors, including yellowish green and olive-green, blue-green, and indigo.
In the past, vivianite was believed to be the cause of the blue color of so-called odontolite. This fossilized bone and teeth material may resemble turquoise. (It’s also called “bone turquoise”). However, heat treatments have been shown to produce the color artificially.
When mined, vivianites are colorless or pale green, but their colors darken after exposure to light. As a result, an enthusiast may find an attractive color disappearing over time. Not surprisingly, this further de-incentivizes cutting an already challenging stone. Still, the appeal remains.
Like its coloration, vivianite’s streak starts colorless but becomes dark blue over time. Please note: don’t conduct streak testing on finished gems. Test material in inconspicuous spots as a last resort only.
Gem cutters rarely facet vivianites, and their almost micaceous cleavage makes polishing gems very difficult. For example, the Bolivian material could yield cut stones up to 75-100 carats. However, this just doesn’t occur.
Due to its fragility, this gem material would make an improbable jewelry stone. Store your vivianite specimens out of the light to protect their color. Consult our gemstone jewelry cleaning guide for more recommendations.