Proustite Value, Price, and Jewelry Information

The Proustite gem is sometimes mistaken for a ruby due to its similar look to a ruby stone. It is one of the rarest gems globally, with colours ranging from red to slightly pale reddish. Its lustre is unique and metallic-like, sometimes called 'silver ruby.'

Proustite jewellery

As an article on Wikipedia says, Proustite is a sulfosalt mineral made up of silver sulfarsenide, Ag33 also referred to as ruby silver or light red silver, which is wonderfully a vital source of the metal. The gem got its name from  Joseph L. Proust in 1804, who analyzed its composition distinguishing it from its look-alike, sulfosalt mineral, and pyrargyrite.

Does Proustite Make a Good Jewelry Stone?

Proustite is good for many things other than jewellery making. They possess silver which poses a risk of irreversible photochromic effect if worn. Their low hardness of 2-2.5 on the Mohs scale makes them not an option for jewellery. This means they are vulnerable to several scratches, even from simple household objects. They are not good for strong light since the stone turns black due to light exposure.

(Proustite | Rock & Gem Magazine, 2019) stated that exposure to light that leaves the stone dull or black makes it not a choice for jewellery. This means that when its beauty fades away, the owner will likely get bored of it.

Proustite stone might be similar to pyrargyrite; however, Proustite is far rarer than pyrargyrite in jewellery making, especially in faceted gems.

 

Is Proustites Safe to Wear?

With the presence of arsenic, dust from this gem, especially when being faceted, should be avoided since it is harmful when ingested. Swallowing or putting the gem in your mouth or leaking your silver onto the gem while conducting local gem tests should be avoided.

However, Joel E. Arem, Ph.D., FGA, argued in his article Proustite Value, Price, and Jewelry Information that there should be no health risks in wearing or touching fully finished proustite gems. 

The stone might have portions of silver which might pose a risk of irreversible photochromic effect (Amber Value, Price, and Jewelry Information, n.d.).

Characteristics of Proustites

(Arem, 2022) wrote that the stone is made of a shiny red streak that makes it remarkable from other gems. Testing the streak on the gem isn't advisable on finished proustite gems. The stone should be adequately tested in sensitive areas in case of identification.' 

Proustite crystals become dull black and opaque if exposed to light for longer periods. Most of the crystals are opaque or translucent though their transparency differs from specimen to specimen. 

Proustite has a unique law of definite proportion where chemical compounds often gather in constant proportions. This was discovered by Joseph-Louis Proust (September 26, 1754, Angers, France – July 5, 1826, Anger, France).

Proustites are also among the few gems that aren't fully synthesized, and there are traces of ideas about the stones' treatments or enhancements.

When exposed to light, Proustite's dull or black colour can easily be eradicated with proper brushing of the stone with soap and water, so it is nothing to worry about.

The crystal has a specific gravity of 5.57 (g/cm3) and a refractive index of 2.792 - 3.088 uniaxial (-0). It has an attractive adamantine lustre that is good for viewing.

The blackening that occurs when a proustite is exposed to light for a long period can occasionally leave an irreversible photochromic effect that might affect the stone's quality. That is why it is recommended that the stone should be stored in dark places with limited light exposure (Arem, 2022).

It is also nicknamed "the blood of the bull" due to its uniquely attractive colour. The name happened in Chile and Chanarcillo, and it is often used when the gems are found in quantity as "Sangre de Chile."

Are There Synthetic Proustites?

Synthetic proustites are made for research-related solutions through optic mixing and lasers. The same method is used to treat or enhance the gems.

Where is Proustite Found?

The finest and best Proustite comes from Chile. The country produces more clear, deep red, and big proustite crystals than any other country. In Chile, places like Dolores Mine in Chanarcillo produce as much as 6 inches and are thick in appearance. 

Germany also has some fine prostitute mines, especially in places like Freiberg. Other crystals come from Canada, Mexico, the United States, and the Czech Republic.

Proustite Stone Sizes

The biggest Proustite ever known today lies in the Smithsonian Institute, weighing 9.9 carats, and it originated in Germany. However, records say that the National History Museum in London has several good-quality proustites in the gem market. 

How to care for Proustites

Taking care of your proustite gem shouldn't be a hard thing. Use a soft, damp cloth, mild detergent, or a brush to clean the crystal. Any relatively hard force incurred on the gem can easily harm its appearance and value.

As this article mentioned earlier, keeping proustite stone in dark places where little or no light reaches it is advisable. This will preserve the beauty and brilliance of the stone. 

Is Proustite a rare mineral?

The deep-red colour and metallic surface lustre make Proustite a rare stone. Besides, only a handful of countries produce this rare gem, making it rarer than so many other gems. 

Also, the fact that Proustite isn't good for jewels makes its demand slightly lower than other gems. And yeah, gem collectors love having these gorgeous gems in their collection, but gem cutters who do it for business tend to be 50/50 on the gem since very few people consider it for jewellery making. However, this doesn't mean that the stone has no value or is not loved. It still has various uses for educational purposes (Proustite Value, Price, and Jewelry Information, n.d.).

What is the meaning of Proustite?

Definition:

Proustite, as I wrote above, is a mineral consisting of a red sulfide of silver and arsenic, and it grows into tiny sizeable crystals and sometimes big, massive ones. To someone new in the gem field, or if you haven't done enough research, you will mistake it for pyrargyrite as both stones share the same colour and nickname "ruby silver" as written above and the same structure even if the chemistry is much different.

Reference:

Arem, J. E. (2022, May 10). Proustite Value, Price, and Jewelry Information - International Gem Society. International Gem Society; www.gemsociety.org. https://www.gemsociety.org/article/proustite-jewelry-and-gemstone-information/

Proustite | Rock & Gem Magazine. (2019, May 23). Proustite | Rock & Gem Magazine; www.rockngem.com. https://www.rockngem.com/proustite/