The facts
What prase actually is
Mineralogically, prase is quartz with actinolite inclusions — SiO₂ + actinolite inclusions, crystallising in the trigonal system.
The colour is caused by leek-green from included actinolite or hedenbergite fibres. That is worth knowing because it determines what heating, light and time can and cannot do to the stone.
A refractometer reads 1.544–1.553, and the specific gravity sits near 2.65; cleavage is none.
Where prase comes from
The recognised sources are Serifos, Greece, Breitenbrunn, Saxony, Germany and Val Malenco, Italy.
Origin affects price in this material, so we name the locality on every quote rather than the country. "African" or "Asian" tells a buyer nothing.
How prase is treated
Untreated. The name is also loosely applied to green chalcedony, which causes confusion in older literature.
None of this is a problem when it is said out loud. It becomes one the moment it is left out.
What prase is confused with
The usual confusions are Chrysoprase, Prasiolite, Green aventurine and Nephrite.
The separation is rarely a matter of opinion: refractive index 1.544–1.553 and specific gravity 2.65 settle most of it in a minute, and magnification settles the rest.
What prase is used for
Prase is bought by mineral collecting, carving and sculpture and decorative objects — and each of those trades wants a different form of the same material.
We quote each application in the unit that trade actually buys in, by the specimen, by the block or by the piece.
Durability and care
Hardness 7; cleavage none. That combination decides what it can safely be set into.
With no cleavage plane to worry about, the practical limit is abrasion rather than breakage, and it takes daily wear well.
Warm water, mild soap and a soft brush. Avoid ultrasonic cleaners on anything fracture-filled, stabilised, dyed or visibly included.
What prase costs
Indicative pricing for prase is $1–10/ct.
That is a range, not a quote. Colour, size, clarity, cut and origin move the figure a long way inside it, and the only honest price is one given against a specific stone. Send us what you need and we will price it.
Questions
Is prase treated, and how?
Untreated. The name is also loosely applied to green chalcedony, which causes confusion in older literature.
Where does prase come from?
Serifos, Greece, Breitenbrunn, Saxony, Germany and Val Malenco, Italy. Origin affects price, so we name the locality rather than the country on every quote.
Is prase hard enough to wear every day?
Yes. At 7 on the Mohs scale with no cleavage plane, it handles daily wear well. The practical limit is gradual abrasion rather than chipping.
How much does prase cost?
Indicatively $1–10/ct. Colour, size, clarity and origin move the price a long way within that, so treat it as a range and ask for a quote against a specific stone.
What is prase confused with?
Most often Chrysoprase, Prasiolite, Green aventurine and Nephrite. A refractive index of 1.544–1.553 and a specific gravity near 2.65 separate it quickly.
What is prase used for besides jewellery?
mineral collecting, carving and sculpture and decorative objects. Each of those trades buys it in a different form and a different unit.
Related stones
Looking for prase?
Tell us the size, the quality and what it is for. We source it, photograph it and quote it — with the locality named.
Ask about prase