There was a time when no respectable casserole or Jell-O salad was served in anything but a brightly colored piece of Pyrex glassware — and every cupboard was stacked high with the functional mixing bowls, baking dishes and storage containers.
Now, Pyrex dishes are fetching big bucks as dealers make rare finds they call the "holy grail" and snap up nostalgic kitchen pieces as seen in their favorite Netflix shows.
Social media has helped people spread the word — and the enthusiasm.
"I didn’t know what I had found at the time," Louis Prizzi, 35, a vintage dealer in Long Island, New York, told Fox News Digital. "I posted it on the Midcentury Modern Kitch Facebook group and people flipped out."
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Prizzi runs an Instagram vintage store called @Thats_So_Loopy.
He casually picked up a small blue Pyrex "Butterprint" bowl at a flea market, which he turned around and sold for $2,100 on eBay after the reaction he got from Pyrex enthusiasts online.
He explained that while the pattern itself is not particularly rare, the small bowl he happened upon was an "unproduced" size that matches a popular four-piece set of mixing bowls.
"So, it’s a never-produced fifth piece — and that’s the reason it is rare and desirable, and commanded that price," Prizzi said.
"Most people were unaware a smaller size even existed. It was probably a promotional piece, and it is said there are less than 10 of them in existence."
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At Cedar Chest Antique Mall in McGregor, Texas, store manager Tim Dowdle said a set of bowls in the harder-to-find "Gooseberry" print, produced between 1957-1966, sold for $699 last month.
But Paulette Kilpatrick, who sells vintage kitchenware and linens at Cedar Chest in McGregor, said the term "holy grail" is a matter of perspective, not just price, when it comes to Pyrex.
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"I recently sold a dish to a young woman that she said felt like was the ‘holy grail’ for her," Kilpatrick said.
"It was a small black casserole with a white interior — and there are very few in black."
It didn’t go for $1,000, Kilpatrick said. But she sold it for $100 and said she was glad she could connect someone with a piece that spoke to her.
Alyssa Durante, 30, of Long Island, agreed with that idea.
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"For me, it’s more of an excitement or an emotional thing," Durante told Fox News Digital. "I do have a vintage Pyrex book that I use to find the value and the history of each piece. But I don't necessarily go for the most expensive pieces. I’m never going to be able to afford ‘Lucky in Love.’"
"Lucky in Love," a one-quart casserole dish featuring green grass and clovers with pink hearts scattered throughout, was most likely a test piece or limited release item that was made only in 1959, according to the Corning Museum of Glass, a not-for-profit in Corning, New York.
In 2015, one dish sold for over $4,000 on eBay.
Popular TV series like "Mad Men" and "The Marvelous Mrs. Maisel" have put certain Pyrex patterns — such as "Turquoise Snowflake" and "Pink Daisy" — in the limelight, Duranted noted.
That and the lure of nostalgia apparently have collectors hitting garage sales and online auctions alike.
"I loved the show "The Marvelous Mrs. Maisel," Durante said. "I felt like I identified a lot with the main character, Midge. I would notice the different Pyrex sets in the background of her kitchen. I was like, ‘Oh my gosh, I have to have the Pink Daisy casserole now.’"
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Currently, there are "Pink Daisy" casserole dishes listed on Etsy, ranging in price from $100 to $300.
"Pink Daisy is really desirable because it's high demand and it's pretty rare," Yvette Egan, owner of the Etsy shop, ParkwoodTreasures, told Fox News Digital.
"They only produced the pattern in certain types of dishes. And the latest one I found is really one of the more rare ones. It's called a ‘space saver.'"
Egan of Madison, Wisconsin, said the dishes were "space savers" because they would fit in the refrigerator and go from oven to refrigerator.
"That was a big deal for those casseroles … So, you didn't have to dirty another dish," Egan said.
The Pyrex dishes that Egan has for sale on Etsy are in mostly mint condition — adding a lot of value to them, she said, since some Pyrex can be faded or have small chips.
"I've had people contact me that don't know a lot about Pyrex and ask, ‘Why are you asking so much for that when I’ve seen it somewhere else for $450?’ I say, ’Try to find them somewhere else,’" Egan said.
For example, Egan is selling a set named Pink Pyrex for $2,189.95.
If a dish comes with the original clear glass lid, it is even more valuable, according to collectors.
Kathy Studensky, owner of Thistle Attic at the Cedar Chest in McGregor, thinks it's millennials who like the idea of a more sustainable form of kitchenware.
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"People are moving away from plastic and we’re finding out that glass is safer than plastic and Pyrex is such a good investment because it’s so durable. You don’t use it for a year or two and throw it away. These things almost last forever."
Durante said sustainability is one of the main reasons she shops at vintage and thrift stores — and her Pyrex pieces further her efforts.
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"It’s a very sustainable source because they last for generations," Durante said. "I know some people don't always cook with and use their Pyrex, but I do. I have maybe three display ones, but all of them I use for baking. I made all of Thanksgiving dinner in them one year."
In that sense, Pyrex is a collection that has function, Prizzi said.
"There are a ton of collectors who collect it and they use it," Prizzi said. "There are Pyrex groups on Facebook where you will see pictures of someone who says, ‘I just made banana bread in a dish that is worth $2,000.’"
While durable, Pyrex should be handled with care when washing, say those in the know.
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"A dishwasher is the no. 1 killer of Pyrex," Prizzi said.
"It will kill the shine and make it worthless," said Studensky, who agreed with that.
"No one had dishwashers when Pyrex was first created," she added. "Warm soapy water. The dishwasher will take the sheen off but even then, you can still use it."
Nostalgia, no doubt, plays a part in the fancy.
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"My first memory of a Pyrex bowl was with my grandma," Durante said. "We were making pizza dough in the bowl."
She added, "It was one of the yellow primary bowls, and I'll never forget it. So for me, it brings me back to making pizza with my grandmother, which is really sentimental because she passed two months ago. Pyrex to me now is even more sentimental than it was before."
Durante said that as an early present to herself, she just bought a full set of primary color mixing bowls that she found on Facebook Marketplace.
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"I think people get into it for nostalgia, and then they fall down the rabbit hole and just keep discovering pieces that speak to them," Prizzi said.
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That’s where Kilpatrick suggests starting a collection.
"Find colors that you like or what you remember from your childhood," she said.