10 Most Valuable Glass Insulators: Complete Value Guide

Not many people are aware that glass insulates against electricity. If you are one of the many who are not aware of this bit of fact, you are not alone.

The glass actually insulates against electricity and they are used routinely on electric poles. It may also interest you to know that people collect these glass insulators. They attach sentimental value to them, they buy them at auctions and set them on their shelves in their homes. It is this people’s hobby to collect antique stuff and glass insulators are some of the most valuable collectibles.

This article will show you 10 of the most valuable glass insulators, both those that have been sold or are on display on sellers’ websites.

10 Most Valuable Glass Insulators Worth A Fortune

Vintage Insulator Rare Slag glass
Aqua Star 162 Glass Insulator
 Antique Ice Blue Glass insulator CD 145
Hemingray PAT 1871 Lightening Insulator
Antique Hemingway 19 Glass Insulator
 Purple Zicme CD 154 Glass Insulator
CD162 Brookfield/New York Glass insulator light SCA
Antique industrial modern aqua blue glass insulator
Folembray Glass Insulator
Vintage Slag Akro Agate glass insulator

1. Vintage Insulator – Rare Slag Glasses

Year: 1972

Price: $875

1. Vintage Insulator - Rare Slag Glasses

This is a glass insulator from the 70s in great shape and one of the most valuable on this list. It sells on Etsy for $875. It was made of slag glass. The seller of this insulator on Etsy described it as McLaughlin No. 19- 1897—1972.

Only a few of these were made in 1972 and they all came out different. The color on this one is orange smeared on a white background. It is shaped like milk glass. It is 4 inches tall and in great condition. A collector’s delight. Depending on the lighting where you keep them, this insulator is very noticeable as it takes the surrounding light and makes it its own.

2. Aqua Star 162 Glass insulator

Year: 1900s

Price: $750

2. Aqua Star 162 Glass insulator

This is a rare glass insulator from an unknown period but is antique all the same. It is a rare, gorgeous threaded pin type electric insulator. The color is olive green, shaped with a dome at the top and ringed in the body. It is said to be extremely desirable and rare which is why it is difficult to ascertain when it was made. The consolidated design number is CD 162, and it appears to be in good condition for any collector of insulator glass to consider buying on eBay.

3. Antique Ice Blue Glass insulator CD 145

Year: 1912

Price: $589

3. Antique Ice Blue Glass insulator CD 145

It used to be Bushwick Chemical Works before the company was purchased by James Brookfield in 1869. They made glassware and electric insulators as well. This electric insulator was number 43 in the Brookfield catalog. It was also called Beehive. It’s got a B embossed on the skirt of the insulator. Its current value sits at $589.

4. Hemingway PAT 1871 Lightning Insulator

Year: 1871

Price: $760

4. Hemingway PAT 1871 Lightning Insulator

This is an old authentic aqua greenish tint glass insulator patented by Josephus O. Chambers of Newport, Kentucky. This insulator is so old it ought to be worth more than this. This may happen however as insulator collectors continue to bid for it on eBay. There were more valuable insulators sold for thousands of dollars on eBay in the past, all used to be valued lower.

5. Antique Hemingway 19 Glass Insulator

Year: 1900s

Price: $423.89

5. Antique Hemingway 19 Glass Insulator

The Insulator’s color is a beautiful cobalt blue, thick glass with straw marks and bubbles in the glass. It is hallmarked on one side of it with the raised words “Hemingway 19”. It was made in the USA. It is threaded inside of the groove and measures about 4 inches high and 31/4 inches in diameter. It was recently sold on eBay for $423.89, a price that’s moderately high for antique insulator glass.

6. Purple Zicme CD 154 Glass Insulator

Year: 1900s

Price: $300

6. Purple Zicme CD 154 Glass Insulator

Here’s a rare and one-of-a-kind CD 154 Zicme Glass insulator. There is a chip to the upper wire ridge and a ding to the same area, though not deep. Additionally, there is a crack in the threads that don’t appear to go to the surface.  The insulator is purple, one of the darker shades. It is also very hard to find in mint condition. It is currently worth $300.

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7. CD 162 Brookfield/New York Glass Insulator Light SCA

Year: 1900s

Price: $230

7. CD 162 Brookfield New York Glass Insulator Light SCA

Here’s another antique insulator glass from Brookfield that is worth some money and with the potential to be worth more. Well, because it is antique, and it was made by the glass company Brookfield. Collectors would love to attach some sentiment and prestige to this insulator glass which may raise the bar for it in the nearest future. It is on eBay for $230.

8. Antique Industrial Aqua Blue

Year: 1920s

Price: $243.95

8. Antique Industrial Aqua Blue

Antique Glass insulators were originally made for insulating telephone lines and electric poles in the mid 1800s. Today these beautiful glasses can be converted into whatever the owner deems fit. They are colorful, like this one pictured from Etsy. It is aqua blue with a wide skirt and threads in it. Since they are no longer used for insulation anymore, these ones have been converted into candle holders. It is up for sale at $234.95.

9. Folembray Glass Insulator

Year: 1960s

Price: $203.34

9. Folembray Glass Insulator

Folembray Glassworks was a French company that made insulator glass and was in operation from 1899 to 1954. This insulator glass-turned coat hanger was made in the 1960s. It is one of the most valuable on this list because of its origin and age. The glass is 5 inches in height and 3.9 inches in diameter. It is valued at $203.34 on Etsy.

10. Vintage Slag Akro Agate glass insulator

Year: 1930s

Price: $200

10. Vintage Slag Akro Agate glass insulator

This is one of the rarest insulator glass. It has gone from the work of electric insulation to being used as a car ashtray. Perhaps cars in the 1930s didn’t have ashtrays in them. Regardless, this insulator glass is considered very, very rare. It is sold on Etsy for $200.

What Are Glass Insulators?

What Are Glass Insulators

Glass insulators are made of glass and were used to protect and insulate wooden poles from the electricity that coursed through the wires on the poles. They weren’t only made from glass though. Some were made with porcelain or composite polymer.

They were first produced in the 1850s first for telegraph lines, then for telephone and electric poles.

The companies that made them include Hemingray, Brookfield, and Whitehall Tatum. You would see insulators being used for many different purposes today. They are used for holding candles, hanging coats and so many other ingenious uses.

Glass insulators were generally less expensive than other materials like porcelain. Between 1875 and 1930 were the great glass insulator years. A large number of glass insulators were produced in these years by glass-making companies in the Midwest and East. A few plants were located in Colorado and California.

These companies didn’t only make glass insulators though. They also produced other glassware like fruit jars and bottles.

The predominant color that insulator glass was made in was aqua (blue green). After 1935 the companies started making clear insulator glass. But over the years the colors that were developed went into the hundreds.

These days you can come upon insulators of different shapes, embossed with different names and numbers, initials, patent dates and many other marks.

How To Antique Date Glass Insulators

The major manufacturers each have different ways of dating their insulator glass. Usually, one look at the body of the insulator glass would yield information about the date. For example you may find a number not accompanied by any other number or alphabet.

If you find the number 47 appearing on its own it may likely mean the glass was produced in 1947. Consider three well known insulator glass makers:


The brand furnishes an easy daring system. You need to look for a circle with an A in it. This indicates that the insulator glass was made by Amstrong. Then if this is followed by two numbers, the first one is the mold number and the second one refers to the year it was made.

For instance, the following numbers, (A) 30 47 means, this glass was made by Armstrong Glass company, in the year 1947, and the mold number is #30. This insulator glass was made in 1947.

It is easier to date a glass when you first find out the maker of it.


This brand presents some complications when dating it. The system here is not as exact as it is in Armstrong Glass. Yet, here are some indications that the glass was made by Brookfield:

  • It will have drip points

Brookfield insulator glass, and some others usually have drip points on the edge of the base. Drip points are little dimples or knobs placed along the outside of the skirt or base of the insulator.

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They were invented by Hemingway Glass Company in 1893 to help water pool in the glass and drop away easily. Now if your insulator glass has these drip points, it helps you narrow down the date of manufacture to nothing less further than 1909 or thereabouts when it appears Brookfield started using the drip points.

  • If the color is aqua or green

Then it was made in Brooklyn at least before 1908

  • If it is dark aqua or green

Then it was made between 1906 to 1921, and it was manufactured in plants in Old Bridge.

  • If it is light blue

Then it was made in the years between 1915 and 1921

Finally, Brookfield made insulator glass from 1906 to 1921. So if you have a Brookfield insulator, then it belongs in the years before 1921. This offers some perspective for dating Brookfield Insulators.


Hemingray Glass company tried to make their own dating simpler but even that takes some practice to master. Hemingray insulators based their dating on the year 1930. On the back of the insulator there might be a symbol like 0-3: : . .

The 0 – is inconsequential. But the 3 means 1930 + 3, then each dot after that is an additional year.

All you need to do is count the dots or those little knobs on the base of the insulator glass then add the number you get to the mold year code on the glass. The addition you get is the year the glass was produced.

With practice, you can get the hang of the daring system. If you are new to collecting insulator glass, associating with expert collectors can also help you get proficient at dating insulators.

How Much Are Glass Insulators Worth?

How Much Are Glass Insulators Worth

Antique glass insulators do have an electrifying and interesting history, but you’d be surprised at how much they are worth. Since they’re made of glass which itself isn’t a product that requires too many expensive ingredients to make, insulator glass tends to sell, on average, for $20.

Like all things antique, insulator glass can sometimes sell for significantly higher prices.

When an insulator glass sells profoundly higher, it has to be on account of the manufacturer, or its color of it.

An instance of an insulator glass selling at a higher price is the CD 130.1 Electric Works Insulator (pictured below) made in 1880 which sold for $5,390.

To know just how much your insulator is worth you’d have to know the year it was made, the company that made it and it has to be a color like the one pictured above. The worth of the insulator also depends much on the condition of the glass.

What Are Antique Glass Insulators Used For?

What Are Antique Glass Insulators Used For

Glass insulators have been replaced by better technology. Today they have attained the status of antiquity and are now auctioned at highly arbitrary prices. Yet, these relics from bygone gears continue to fascinate the minds of collectors who continue to hunt them down.

Not everyone who has an insulator glass in their home does so because it is a hobby to collect. The most important use for insulator glass other than selling them is upcycling or using them for other purposes different from their original intention.

Antique glass insulators are used for the following things:

Insulator Glass As A Candle Holder

Insulator Glass As A Candle Holder

Now you can switch off the lights in the evening and conserve energy because you can actually turn your insulator glass into a beautiful candle holder. Dinner nights at home are never going to be the same again after you try this:

Take a typical insulator glass, a colorful one. Get an old bed spring and let the top of the insulator glass go on the narrow side of the spring. The wider side of the bedspring acts as a stable base for the glass. Now you can let your candles sit in the groove of the glass. See an example below.

Insulator Glass As Lantern

Insulator Glass As Lantern

If you have an insulator glass you may not need to purchase a lantern or ditch the one you are using currently. Insulator glass offers a more colorful alternative.

Get a thin wire (wire hangers provide the best material for this). Stretch it out before stringing it around the middle of the glass insulator so that the tapered body is hanging upside down with the base facing up.

Plant your candle in it and hang it on a tree at the back of the house. Evenings in the garden can now be more refreshing with the ethereal light cast by the glass. You may prefer cobalt blue glass for this.

Glass Insulators As Chandeliers

Glass Insulators As Chandeliers

With a bunch of glass insulators, you can create unique artwork from glass insulators to make a homemade chandelier. You need any number of insulator glass for this, plenty of steel wires, and about three meters of dog chain from the basement.

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You can get creative creating your own chandelier. Below is a picture to give you ideas and get your creative juice flowing. Make sure to secure the wires around the glass insulators properly as you latch them to the cagelike contraption you have already built.

You can have it up in the attic, the kitchen, and the porch. Anywhere in the house where the colors of the glass can compliment the decor and give the room a rustic look.

Glass Insulator Industrial Lamp

Glass Insulator Industrial Lamp

Industrial steampunks can have glass insulators fixed in. This would take some expertise though but with the right tools, you should be able to make an insulator glass light like the one below. You can even have one of these on the wall over the headboard.

Glass Insulator As A Vase

Glass Insulator As A Vase

You don’t have to make lamps and chandeliers if you don’t want to. Perhaps you are into gardening and you would love an opportunity to try new ways to plant flowers. Transform an insulator glass into a vase like the one in the picture below. You need a glass of your choice, an old bed spring of scrap wire. You’d be surprised how easy it is to do, and how beautiful they coke out.

Where To Find Antique Glass Insulators

Very few glass insulators are now in use in places on earth. Many of the companies that made them are no longer in operation.  If you are interested in collecting glass insulators you can get them from the following places.

Antique Stores

It is not likely that you’d be able to climb up an electric pole in your area to pluck off a glass insulator. Neither do we still have telegraph poles anymore. But you can find glass insulators in antique stores in your area if you check. You can’t miss them. They were made in different sizes and shapes but all look similar with rounded tops and wide bases. They are colorful too. Many antique stores collect and stock them.

Garage Sales

You may also come across collections of them at garage sales in your locality. People started collecting glass insulators in the 50s and 60s. Many people who did are now old and have probably lost interest in keeping them on. So you might walk in on a garage sale where glass insulators are stacked up for sale. One of the advantages of this kind of find is they sell cheaper than when you buy from antique shops where the stockist himself may have bought from a garage sale.

At Auctions

If you are starting out as a collector of glass insulators, this is one of the best places to find them. One of the benefits of auctions is the antiques are usually in better condition than those at a garage sale; no scratches, chips, or cracks. The downside is they can be pricy at auctions because of their good condition.

Online marketplace

You can find a surprisingly large supply of antique things online. Glass insulators are not left out. Online shops have a section for antiques and they stock glass insulators too.

Examples of such websites are eBay, and Etsy.

The online shop Etsy has more than 1000 items stocked under glass insulators. And they are featured in different colors and sizes, all from different sellers who will ship merchandise to your location at a fee. eBay stocks glass insulators too in their numbers. Amazon is another website where you can find glass insulators. One of the benefits of sites like this is sellers there usually have the integrity to protect so you will usually get what you see.

The downside is you don’t have the opportunity to examine physically what you are buying as you would at a local store or physical auction house. You can only hope that the seller by credible.

Final Thoughts

Glass insulators may not be protecting poles from holding electricity again but as you can see they can now bring light and color to homes. For collectors, these insulators from the past can still bring them a substantial profit when selling to the right buyer. And, if you are in need of some cool glass insulators for your home or to be used for crafts or for your garden, you may want to check out whether or not there is a surprising collection of glass insulators hidden in one of your closets, or stashed away in your basement.

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