Aventurine is the name given to a variation of the minerals quartz and feldspar. More commonly, it is also used to refer to a type of glass said to have been created by accident.
It is said that a Venetian craftsman mistakenly mixed copper shavings into molten glass, resulting in what a German diplomat described in a 1614 letter as “a stone with golden stars within.” Julie Bellemare, curator of early modern glass at the Corning Museum of Glass in upstate New York, said in a telephone interview that the letter may be the earliest reference to aventurine glass.
Aventurine (mineral aventurine and glass aventurine) has soared in popularity among watch brands and watch collectors in recent years. A. Lange & Söhne and Czapek & Cie use aventurine glass dials to evoke the midnight sky with twinkling stars or the mysteries of the universe. Omega uses a mineral version and a glass version.
“No dial is the same, no dial is the same,” said Anthony de Haas, director of product development at A. Lange & Söhne, “but it’s always elegant.”
Dr Bellemare said that throughout the 17th and 18th centuries, aventurine’s basic ingredients – plant ash and silica from sand or quartz pebbles, and copper – were mixed into clay crucibles and fired into large chunks.
“It’s a completely different process than glassblowing,” she said. “The blocks were a square foot, quite large, and you didn’t know if you were going to get what you expected at the end of the shot.” Dr. Bellemare said the recipe was a closely guarded secret and likely changed in the 19th century, when it When changes occur, so do production methods.
Describing how Lange now produces “glass containing thousands of pieces of copper,” Mr. de Haas said the glass is melted and the pigments selected. He said the glassblowers “let it grow like a carrot” and then put pieces of copper into it. “It hardens, and then they cut the carrot into small slices.”
The company’s dark blue glass is then made into the dial in Germany and shipped to Switzerland for polishing.
Mr. de Haas said the brand introduced copper blue, the signature color of aventurine, about five years ago. “People are going crazy,” he said in a video call. “This is the first fancy color thing we’ve done at Lange and the first time the brand has used this material in this price range.”
The Saxonia Thin is a 39mm watch with an 18-karat white gold case and a copper-blue dial that retailed for $22,000 when it launched in January 2018. The current price is $29,000. The company has since used the material in its Lange 1 series of watches, including the Little Lange 1 Moon Phase.
“This midnight blue is gender-neutral yet sophisticated,” Guillaume Chautru, Piaget’s head of gemology, said during a video call. “It’s a premium color that’s chic and anyone will love it.”
Piaget has long been known for its use of minerals and gemstones on its dials, but in the past few years Piaget has begun using aventurine glass instead of lapis lazuli, which it can no longer obtain from Afghanistan.
“Once the glassmakers figured out how to homogenize the color with equal amounts of copper oxide, we knew it was the Piaget color,” Mr. Chotru said.
He said it was always difficult to achieve the 0.4 mm thickness required for a Piaget dial, but it was easier to do so with glass than with natural stone. Piaget currently has seven watches with blue aventurine glass dials, ranging in price from $27,200 for the Limelight Gala watch to $146,000 for the Altiplano Tourbillion.
A collector’s request inspired Swiss independent brand Czapek & Cie’s recent foray into aventurine glass.
“Aventurine dials revolutionize your watch; the way the metal shimmers and reflects is truly mesmerizing,” said Xavier de Roquemaurel, CEO of Czapek, during a video call . “
“Then we have our collectors; they ask for aventurine by name.”
A year ago, an Italian collector commissioned an Antarctique Aventurine that featured baguette diamond hour markers. Mr. de Roquemaurel said that although working with aventurine glass was difficult, he was happy to oblige.
When you have a complex design, he said, “or applied indexes, there’s all the risk, and you might break one of three or four dials in the process.” The dial maker is not aventurine-made Business, although the initial materials are not very expensive, you have to make a minimum quantity.”
The Italian collector has since commissioned a limited-edition collection of 18 pieces, each priced at $45,000 and scheduled to be released around the year-end holidays.
Omega uses aventurine in both glass and mineral stone forms. “The gap between unique natural stone from the earth and glass produced in an industrial way by machines is quite large,” said Gregory Kissling, Omega’s vice president of products for stone and its finished products.
Omega began using this glass in 2013, and it has been used on the dials of 21 of the brand’s watches, including several 29mm Constellation watches.
Gregory Kissling, Omega’s vice president of products, said the brand’s patented glass process involves crushing aventurine glass into a powder that is then used in the enamel. While the end result used in the brand’s De Ville Trésor collection looks like classic aventurine glass, the enamel version suffers from less breakage – two to three dials are broken for every watch that ends up being made. But “that’s the nature of these materials,” Mr. Keesling said in a video interview.
Omega started using aventurine quartz in 2021, purchasing supplies from India and Brazil, but the quartz can also be found in Russia, Tanzania and the United States.
While quartz versions range in color from deep reddish-brown to blue and green, Mr. Keesling said the blue versions were more popular. “Blue is the new black in the watch industry,” he said.
To use aventurine quartz, Omega created a new method of dial construction. A brass base is constructed with proprietary inlays and shapes, and the mineral is then affixed to it. If the watch is dropped or hit, the base can absorb the impact and prevent the minerals from cracking or cracking, Mr. Keesling said.
Mr Keesling said both versions of aventurine were very popular.
“It’s the universe, the stars and emotions,” he said. “Every time we show it, it always produces amazing results.”