The Top 15 Most Valuable Glass Insulators for Collectors in 2023
Glass insulators have come a long way from their original purpose on the cross-arms of telegraph poles. Once vital for insulating electrical currents on telegraph and telephone lines, these humble glass domes are now prized by collectors for their gorgeous colors, interesting embossing, and historical significance.
Whether you‘re an experienced insulator hunter or new to the hobby, learning to spot the most valuable glass insulators can be both exciting and rewarding. Knowing which specific pieces to look for based on their maker, color, age and identifying marks can help you zero in on insulators worth hundreds or even thousands of dollars.
To help you get started, we‘ve compiled the ultimate collector‘s guide to the top 15 most valuable glass insulators. You‘ll learn the history behind these special pieces, what makes an insulator rare and desirable, and how to identify different styles and manufacturers.
Plus, we‘ll reveal the specific insulators that are considered the "holy grails" for collectors, along with real auction prices. By the end, you‘ll be ready to start building (or growing) your own collection of these beautiful bits of history.
A Brief History of Glass Insulators
Before diving into the most sought-after pieces, it‘s helpful to understand how glass insulators were used and why they evolved the way they did. Here‘s a quick primer:
The earliest insulators, dating to the 1840s, were made of glass or porcelain and used on telegraph lines. As telegraph and later telephone networks expanded across the country in the late 19th century, the demand for insulators to prevent electrical leakage grew exponentially.
Manufacturers like Hemingray, Brookfield, and Whitall Tatum began mass-producing insulators in a range of styles, sizes and colors to meet the needs of different lines and voltages. Most insulators were made of molded glass and featured a "pin" style that could be mounted on a wooden crossarm or bracket.
Over time, insulator designs became more specialized and colors more varied, depending on the manufacturer and customer. Hemingray alone made dozens of different styles in shades of blue, green, amber, and clear glass.
The "golden age" of glass insulators lasted from around 1870 to 1930. During that time, hundreds of millions were produced by glass companies across the U.S. But as telephones switched to underground cables and electrical lines upgraded to porcelain, the reign of glass insulators gradually faded.
Today, only a small percentage of lines still use glass insulators. But thanks to the foresight of early collectors, thousands of beautiful examples have been preserved. Now let‘s see which ones are the most coveted by today‘s collectors!
Top 15 Most Valuable Glass Insulators
These 15 glass insulators are considered the "crown jewels" for collectors, commanding the highest prices on the market. Values shown are based on recent real-world auction results.
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CD 130.1 California Electric Works – $8,000
Considered the most valuable glass insulator, this deep cobalt blue piece was used on the first long-distance telephone circuits in California in the 1870s. With its gorgeous color and historical significance, it‘s a true gem for collectors. -
CD 141 Twiggs Insulator – $4,000
Named for inventor J.M. Twiggs, this massive aqua glass insulator features an unusually shaped "hourglass" dome meant to securely grip wires. Very few of the originals still exist. -
EC&M Clear/Aqua Glass Insulator – $2,500
These small, stout insulators were made by the Edward Caulkin & Merrimac company for use on early telegraph lines out West. Examples in pristine condition are extremely rare. -
CD 143 Fry Glass Company – $2,000+
Beautiful royal blue insulators embossed with "FRY GLASS CO" were produced for a few short years in the 1870s for high-voltage lines. Their rich color and scarcity make them highly sought-after. -
CD 162 H.G.CO "Mickey Mouse Ears" – $500-$1,200
Hemingray Glass Company‘s attempt at a more secure wire-gripping design resulted in this quirky, cartoon-eared profile. Pristine examples in colors like royal blue, amber and yellow olive can top $1,000. -
CD 133 "Coolidge Drip Points" Insulator – $600-$1,000
Invented by engineer O.S. Coolidge, the pointed "drip points" under the dome of this clear glass insulator were intended to shed water away from the wooden pin. The unusual feature adds to its collectible appeal. -
"Fletcher" CD 103 Brookfield – $200-$800
Bold cobalt blue insulators embossed with "FLETCHER‘S / PATENT / BROOKFIELD" were some of the earliest produced by Brookfield Glass Company in the 1860s. Their age, color and historical ties make them very desirable. -
Hemingray-42 or "H-42" – $50-$600
The iconic Hemingray-42 is one of the most widely-produced and collected insulators. Common in aqua and green, rarer colors like yellow, amber, and "Hemingray blue" can command hundreds from collectors. -
CD 154 "Petticoat" Insulator – $75-$300
This shapely insulator got its nickname from the flared, ruffled skirt design. Originally produced for telephone and telegraph giant Western Union, examples in colors like sapphire blue are highly sought. -
CD 162 with "PATENT PENDING" embossing – $100-$200
Most CD 162 Hemingray insulators have "MAY 2, 1893" embossed on the dome. But a few rare examples found with just "PATENT PENDING" are considered more valuable by collectors. -
CD 102 H.G.CO "Pony" Insulator – $40-$150
Standing just 3.5" tall, these compact, sturdy insulators were widely used on short telegraph lines. Common in aqua, rarer colors like emerald green, amber, and shades of blue are most collectible. -
CD 120 "Toll" Insulator – $100-$200
Made for use on long distance "toll" telephone lines, these clear or aqua glass insulators have a distinct straight-sided profile and wide, rounded dome. Examples with "TOLL" embossing are most prized. -
CD 257 Hemingray-19 "Blob Top" – $20-$125
Featuring a bulbous shape and rounded dome, the "Blob Top" insulator was another attempt at a high-voltage design. Today, examples in yellow, amber, and jade green are favorites with collectors. -
U-976 "Thomas" Insulator – $50-$200
With their unique straight-sided shape, Thomas insulators were produced by McKee Glass Company for just a few years in the 1920s. The original aqua color is common, but rare colors like purple and amber are coveted. -
CD 121 "Cal Electric" Mickey Mouse
Last but not least are the adorable "baby brother" to the CD 162 Mickey Mouse: the tiny CD 121 in beautiful shades like blue, green, and purple. These bite-sized beauties can still bring $50-$100 apiece.
Guide to Valuing Glass Insulators
Now that you know some of the most valuable glass insulators, how can you evaluate pieces in your collection or ones you come across in the wild? Here are the key factors that influence an insulator‘s value:
Design/CD Number: Consult insulator price guides to ID a piece based on its shape and CD (Consolidated Design) number. Certain designs like the Mickey Mouse, Petticoat, Thomas, etc. tend to be most collectible.
Embossing: Insulators were often embossed with manufacturer‘s marks, patent dates, and customer names. Unusual or historically significant embossings can make an insulator more valuable.
Base Type/Shape: Certain base profiles (the area around the insulator‘s "skirt") are more desirable, like the "Petticoat" flare and "Toll" straight sides. Very early threaded bases are also scarce.
Color: In general, the rarer the color, the higher the price. Brilliant jewel tones like cobalt, sapphire and purple are most coveted, along with yellow, amber, and uncommon shades of green.
Condition: An insulator‘s value drops sharply if it has any cracks, chips, or dings. Pieces with a pristine, shiny surface and no blemishes will always command the highest prices.
Where to Find Antique Insulators
One of the joys of insulator collecting is hunting for new pieces to add to your collection. Some of the best places to look include:
- Live auctions and insulator shows
- eBay and online collectors‘ marketplaces
- Flea markets and antique shops
- Old railroad tracks and abandoned lines (always get permission)
- Networking with other collectors
Creative Uses for Insulators
Beyond their value as collectibles, antique glass insulators have a beautiful, nostalgic quality that makes them popular for crafting and home décor. Some creative repurposing ideas include:
- Stringing insulators on a wire to make a unique fence topper
- Wiring them into a pendant lamp or patio string lights
- Using them as candle holders or vases
- Displaying them on a windowsill to catch sunlight
- Embedding them in a concrete garden path
- Gifting special insulators to other history/telegraph buffs
We hope this guide has given you a new appreciation for these humble yet historic little objects. Thanks to their quirky charm and the thrill of the hunt, insulator collecting is a hobby that continues to gain devoted new fans.
While only a lucky few may find a CD 130.1 or Twiggs, starting your own collection of glass insulators is easy and affordable. And who knows – that aqua Hemingray-42 you picked up for $5 may end up being worth much more in the future!
So the next time you spot an old glass insulator at a flea market or antique shop, take a closer look. With a bit of knowledge and a knack for spotting the rare gems, you‘ll be on your way to building a collection that‘s both personally rewarding and financially valuable. Happy hunting!
