Seth Thomas Clocks Value & Dating Guide (Models & Marks ID)

Imagine looking at your living room’s walls and finding an old Seth Thomas ticking clock with intricate brass movements and carved wooden cases, that could be worth thousands! Sounds enticing! But how can you determine the true value of your vintage Seth Thomas timepiece?

From spotting the telltale “ST” logo to decoding date stamps and movement details, this detailed value guide will unravel important keys to identifying and valuing antique Seth Thomas clocks!

Brief History of Seth Thomas Clocks

Antique Seth Thomas Wall Clock

The legacy of Seth Thomas Clocks began after American clockmaker Seth Thomas established the Seth Thomas Clock Company in Plymouth Hollow in 1813. The company soon became known for producing high-quality timepieces. 

These timepieces include iconic wall and tabletop clocks, premium mantel clocks, and long-case clocks from the late 19th century. Known for their traditional clockmaking components, such as chimes and pendulums, antique Seth Thomas clocks are extremely popular among collectors. 

In the early 20th century, the company continued manufacturing different types of traditional mantel clocks, grandfather clocks, and pocket watches. In the mid-20th century, it adapted to technology and introduced electric and atomic clocks. 

After mass-producing timeless clocks for over 150 years, the Seth Thomas Company merged with the General Time Corporation and was sold to Talley Industries. Later, the men’s accessories company Colibri Group owned Seth Thomas Company. 

Key Identification Features of Vintage Seth Thomas Clocks

Shelf Clock Shape

While most Seth Thomas clocks are collectible, today, some special ones are worth the most. Here are some key features that make an antique Seth Thomas Clock special and valuable:

  • Wooden case (especially mahogany wood) with ornate scrollwork
  • Original painted dials with Roman numerals with the company’s logo or name
  • Well-functioning clock movement with engraved markings 
  • Working movement with accurate timing 
  • Original paper or metal labels stamped on the clock case
  • A rare model with a unique shape or dial color, clock style, or mechanism

Assessing the Value of Seth Thomas Clocks in 5 Steps

Common, well-preserved old Seth Thomas clocks can be worth around $100 to $500 today, while rare, high-end pieces in excellent condition can fetch extraordinary returns as high as $2,000 to $3,000 or even more. Just like this Seth Thomas Office Calender Clock #13 I found on eBay that sold for almost $3,000!

Screenshot 2024 06 26 195634
Source: eBay – thib-7

The final resale value of an antique Seth Thomas clock depends on several factors, such as its condition, working mechanics, clock type, and age. Considering this, you can estimate your ST clock’s worth using the following steps.

1. Examine the Condition

The first step to appraise a vintage Seth Thomas clock is to check the overall condition of the case, clock, movements, and dials inside out. While doing this, remember these points: 

  • Clocks with properly running movements that keep accurate time are more valuable than those that do not run or keep poor time.
  • Original, undamaged clock cases in pristine condition are valued more than those with repairs, replacements, or significant damage, like cracks, chips, and severe crazing.
  • Wooden cases with old, visible patina are adored by collectors. 
  • Movements with all original parts make the clock more valuable while replacements or missing movement components will lower its worth. 
  • Broken dials or those with big cracks, faded paint, and missing or unreadable numbers are much less desirable. 
  • Broken or cracked clock face glass will also depreciate the clock’s overall value.

2. Identify the Type of Clock

Old Mantel Clock with Colored Dial

The value of a Seth Thomas clock may also depend on its type, as different clock types have distinctive features and appearances. For example, a grandfather clock or longcase clock will usually cost more than a wall clock due to its large size and ornate wooden case. 

Seth Thomas’s most popular timepiece types are: 

  • Pillar & Scroll Shelf Clock (Mantel or Desk Clock): Wooden case with decorative pillars and scrolls, brass movements & painted dials
  • Wall Clocks: Weight-driven movement with a long wooden case and pendulum
  • Adamantine Mantel Clock: Adamantine (a type of veneer) case and 8-day spring-driven movement
  • Sonora Chime Clock: Spring-driven movement, quarter-hour chimes with tubular bells.
  • Office Calendar No. 6 Wall Clock: 8-day spring-driven movement, roll-type calendar, separate seconds dial.
  • Grandfather Clock: Tall, freestanding clock with a long wooden case, brass 8-day weight-driven movement
  • Alarm Clock: Spring-driven movements to make the alarm sound at a designated time, metal or Bakelite cases. 
  • Pocket Watch: Hand-winding movements with jewels

Seth Thomas Mantel clocks are the most popular and sought-after among these types. The value of an old Seth Thomas mantel clock ranges from $200 to $2,000 or more, depending on the condition, case, model, and age.

3. Observe the Rarity & Demand

To assign a price to a Seth Thomas clock, you must know whether it’s a rare or common model. Why? Certain ST models, especially from the late 19th century to the early 20th century, are extremely rare to find today. That’s why collectors are ready to pay hefty prices for them. 

For instance, I found this rare Seth Thomas 8 Bell Sonora Chime Clock No.266 that sold for a whopping $3,250 on eBay.

Screenshot 2024 06 26 194953
Source: eBay – agreattimetobuy

Similarly, clock models that were part of a limited edition or special series, belonged to a significant time period, or were owned by a significant figure could be highly desirable and worth a few thousand. 

The best way to find out if a Seth Thomas clock is rare is to research the specific model to see if it’s easily available or was a limited production run. Also, observe the sales prices of such rare models to understand their actual worth for collectors.

4. Look for Special Designs or Features

Branded shelf clocks
Image: Mark James Miller, CC BY-SA 3.0, via Wikimedia Commons

Seth Thomas clocks that offer unique features, such as perpetual calendars or moon phase indicators, special dial designs, double clock style, and unusual case materials, are considered valuable. 

For example, a rare Seth Thomas Double Time Hanging Clock (Regulator No. 6) was auctioned on LiveAuctioneers for an exceptional price of $12,000.

Quick Tip: To check if your Seth Thomas clock has any special features, compare its features to other known models available online.

5. Find the Age

Naturally, older Seth Thomas clocks in working condition from the company’s early days are highly desirable and precious, as they have withstood the test of time. This means clocks dating back to the early to mid-19th century are valued the most by collectors. 

For example, a rare American Federal tall case Seth Thomas clock from 1820, is currently listed at $15,000 on 1stDibs. Here, the type of the clock also adds to its amazing worth.

Screenshot 2024 04 30 182243
Source: 1stDibs

Identifying & Dating a Real Seth Thomas Clock

As mentioned above, for a Seth Thomas clock to be valuable, it has to be old and antique! But, how will you spot such old timepieces and find their approximate age? Well, there are important clues that will help you identify and date your Seth Thomas clock.

Stamped Label with Trademark

Genuine vintage Seth Thomas clocks have a label that verifies their authenticity. Most clocks have the paper labels glued inside, at the back, or on the bottom of the case, but some may also have a metal label stamped or screwed to the case.

Screenshot 2024 04 30 185934
Source: eBay – 7podolany

This label is a crucial identification clue as it displays the company’s name, trademark, location, and, in some cases, model or style number and name as well.

Since the company upgraded and modified its trademark over the years, the company logo printed on the label can also serve as an important dating clue for an old Seth Thomas clock. You can refer to the Labels Trademarks section on the official website of Antique Clocks Identification and Price Guide to date your clock based on the logo design.

Note: A missing label will not only depreciate the value of a Seth Thomas clock, but it may also indicate that it’s likely a counterfeit.

Date Stamp Markings

The next crucial clue to look for is the dating code, which is the manufacturing date (year) marked/engraved at the bottom of the clock case. This date code has four numbers and a letter, in which the numbers are the manufacturing year spelled backward, and the letter (from A to L) represents the month. 

For instance, if an antique clock bears the code “9881B,” it means it was manufactured in February 1889.

Movements (Style & Markings)

The movements of the vintage Seth Thomas clocks may display different engraved markings to help you identify and date them. For example, the mid to late 19th-century clock movements likely bear the “S. THOMAS/PLYMOUTH CONN/U.S.A.” marking, often with the “ST” inside an encircled diamond logo.

Seth Thomas Clock Movement Mark

In some clocks from the late 1800’s to early 1900’s clocks, you may see the “ST” logo with “MADE IN U.S. AMERICA” next to it. Generally, most early to mid-20th-century Seth Thomas clock movements have the “ST” logo with “MADE IN U.S.A” written around the circle.

Seth Thomas Clock Movement ST Marking
Seth Thomas Clock Movement Marking

In addition, the movement may also have numbers, like “120,” “77A,” or “48N” engraved on it. These are model numbers that can help you identify the model of your Seth Thomas clock. 

Another dating clue is the design of the movement plates. Antique Seth Thomas clock movement plates before the 1950s were rather plain, with a simple “ST” logo and the “USA” location mark. But if you notice small bumps or pits on the clock’s movement plates, it was most likely manufactured in Germany between 1950 and 1980. 

The movement style used in an ST clock can also help in tracking its age. For example, if the clock has a “Cottage” clock movement, it likely dates back to 1870 to 1877. If it’s Ansonia’s “Royal Bonn” clock movement, it was made from 1886 to 1898. Clocks manufactured after WWII often have Hermle’s clock movements. 

Clock Materials


The pre-1840s antique Seth Thomas mantel clocks mostly used wood movements with scroll designs. In 1840, the company began using brass movements, which were then used throughout the company’s history. Some later clocks (from the mid to late 20th century) may have movements with steel components.

Clock Cases

Most Seth Thomas clocks, especially shelf clocks and wall clocks, from the 19th century to the late 20th century have a mahogany case with scrollwork. Some clocks might have oak, walnut, or cherry wood frames. 

Besides, some alarm clocks from the 1930s and 1940s may feature bakelite cases, which are generally worth less. I found one non-working Seth Thomas Bakelite alarm clock that sold for $170.

Screenshot 2024 06 26 181041
Source: eBay – rca10000

Clock Dials

Most late 19th and early 20th century Seth Thomas clocks have dials made of painted metal, but some higher-end clocks may also have porcelain dials.

Adamantine Cases

In 1881, Seth Thomas Company acquired the license to use the Adamantine veneer, which the Celluloid Manufacturing Company had developed and patented in 1880. In 1882, Seth Thomas began manufacturing mantel clocks with Adamantine veneer cases.

Antique Seth Thomas clocks hold a significant monetary value today. Flaunting the conventional 19th-century clock mechanics, these timepieces are worth collecting, just like old Waltham Pocket watches which are hidden gems with unexpected value today!

Judith Miller
Judith Miller

Judith is an antique expert with nearly 20 years of experience in the field of antique identification and valuation. She has reviewed over 30 thousand vintage items and has worked with numerous antique shops. She enjoys seeing new places, attending antique shows and events, and sharing her knowledge with people! Know more about me

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