Heisey Glass: The 1911 Patent Behind the Shine, and the Mark Imperial Kept Using

By Matthew Partsch · Owl and Twig Vintage · October 1, 2026

A.H. Heisey patented the fire-polishing process that gives early pieces their smooth, almost liquid surface — the same quality collectors still run a fingertip across to test today. What a 1911 patent can't settle on its own is the mark. When Imperial Glass bought Heisey's molds in 1958, it kept stamping Heisey's own Diamond H on glass the factory never touched.

The patent behind Heisey's fire-polished shine

A.H. Heisey & Company was formally incorporated in April 1896, when its newly built factory in Newark, Ohio began production. For its first four years on the floor, none of that glass carried any maker's mark — a plain pressed tumbler from Heisey's own factory in 1898 is, by the company's own later account, indistinguishable at a glance from a dozen competitors' tumblers of the same year.

That changed around November 1900, when the company settled on a mark: a capital H set inside a diamond, said to borrow its shape from founder Augustus Heisey's own college fraternity badge. It appeared in Heisey's advertising that same year and was formally in place by August 8, 1901. Heisey is widely credited as the first American glass company to mark its own tableware this way — a decision competitors spent the next several decades following.

A mark alone doesn't explain why a piece of Heisey glass feels different in the hand, though. That comes from a patent. On June 26, 1909, company inventor Andrew J. Sanford filed for "Method of Fire-Polishing Glassware"; the Patent Office granted it May 30, 1911, as U.S. Patent 993,555, assigned to A.H. Heisey & Co. The method: support a molded glass article fully on a shaped form, rotate it, and direct flame jets across the top and bottom surfaces at calculated angles — high speed first to finish the top, then a slower pass for the underside — so the piece re-melts its own outer skin smooth without losing its shape. It is, in the inventor's own words, a way "to provide for the fire polishing of both the top and bottom faces" of a piece while removing the mold marks and surface imperfections a plain pressed article would otherwise carry.

That process is the reason a present-day identification guide can tell a collector to run a fingertip across a piece and expect "fire-polished smoothness, faint mold seams" from genuine early Heisey — the patent describes, in 1911, the exact manufacturing step that produces the texture a buyer is checking for more than a century later.

One set of molds, two later owners

The Newark factory closed in December 1957 for its usual holiday break and never reopened. In 1958, Imperial Glass Company of Bellaire, Ohio bought what was left of the business on paper: Heisey's own account describes the sale as covering "moulds, tools, patents, copyrights, formulas and more." The Smithsonian's Archives Center, in its own finding aid for the Imperial Glass Company Records, confirms the same transaction in a single sentence of its own: "In 1958 Imperial Glass purchased molds from the Heisey Co." One identification guide puts the number of molds acquired at roughly 4,000; that specific figure was found in only that one source for this guide and is given here as reported, not independently confirmed.

What happened next is the wrinkle this guide turns on. Imperial did not strip Heisey's mark before putting those molds back to work. By one identification guide's account, Imperial kept applying the authentic Diamond H to pieces made from Heisey's own molds for roughly a decade, until 1968, before its own production became more reliably distinguishable. That specific cutoff year was not found corroborated elsewhere in the sources checked for this guide. What multiple sources do agree on, independently, is the broader and more useful point: Imperial made many of those same shapes in colors A.H. Heisey & Company never produced. Color, not the mark by itself, is the identification test collectors actually lean on.

Imperial itself closed in 1984. What molds survived that closure passed again, this time to the Heisey Collectors of America, the club that also runs the National Heisey Glass Museum in Newark. HCA has since commissioned further limited reissues from original Heisey molds — made, depending on the shape, by Fenton, Dalzell-Viking, or Mosser — marked with an HCA cipher and produced deliberately only in colors neither Heisey nor Imperial ever used. A shape that started in 1896-to-1957 Heisey production can, by the time it reaches a shop shelf today, represent any of three separate manufacturers working from the identical mold.

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How to tell a real one

None of the four checks below settle an attribution alone. Used together, they narrow a piece down to one of the three production eras described above.

• Check the color before anything else. Imperial made Heisey's old shapes in colors Heisey itself never produced — caramel slag, milk glass, amber, and a color called heather among them. A piece in any of those colors was not made before 1958, whatever mark it carries.
• Run a fingertip across the surface. The 1911 fire-polishing patent is why genuine early Heisey has a smooth, almost liquid finish with faint mold seams. A duller finish and heavier seams point to later production, consistent with Imperial's own less exacting finishing process on the same molds.
• Feel the mark, don't just look at it. A genuine molded-in Diamond H sits as a small raised bump above the surface. A mark that reads scratchy or sits below the surface was added after the glass left the mold — worth treating as a separate problem from the mold-era question entirely.
• Match the pattern to the color's actual production years. A pattern-and-color combination that postdates when a given color was in use anywhere in Heisey's own output is a mismatch worth tracing before trusting the piece's story.

The look-alikes

Heisey's own catalog of pressed glass animals — birds, horses, farm animals, dolphins — is usually credited to designer Royal Hickman, the same designer behind Haeger Potteries' mid-century figural lines (covered in this guide's look at Haeger's own marks and model numbers) — one designer working in both pressed glass and ceramic slip at roughly the same moment in the 1930s and 40s. Among Heisey's animals, the Chanticleer, or Fighting Rooster — catalog No. 1557, a clear glass vase in the shape of a crowing rooster, produced roughly 1939 to 1946 — is one of the most widely reissued shapes, which makes it a working example of all three eras described above.

A buyer who wants specifically pre-1958 Heisey production needs all three columns, not just the mark — a clear crystal Chanticleer with what feels like a genuine impressed Diamond H could, on the current state of the record, still be a piece Imperial made after the original company was gone.

Where the records disagree

Heisey's own founding year is not quite as settled as a single company history suggests. The National Heisey Glass Museum describes the company as "formally incorporated" in April 1896, when its Newark factory began production. Wikipedia's account of the same company gives 1895. Neither source was checked against the other's underlying citation for this guide; both are given here as reported, a year apart.

A third, more surprising figure comes from an institution with no obvious reason to get the date wrong: the Smithsonian's own Archives Center, in its finding aid for the separate Imperial Glass Company Records collection, describes the business it bought molds from in 1958 as "the Heisey Co. (est. 1885)" — eleven years earlier than either of the other two figures. This guide found nothing supporting an 1885 founding independently, and the most likely explanation is a dating error inside that one finding aid rather than a third, unrecorded company history. It is named here rather than quietly corrected, in keeping with this guide's own standing practice: a primary archival record disagreeing with the rest of a company's documented history is itself worth a reader's notice, whatever the likely cause.

The Diamond H's own adoption date resolves more neatly into a sequence than a contradiction once both sources are read together: designed and first used in advertising in 1900, by the Heisey museum's own account, and "officially approved" — most likely meaning a formal internal or legal step — on August 8, 1901, by a National Depression Glass Association collectors' journal's account. Most retellings compress this to a single year; the fuller record has two dates roughly nine months apart.

Least settled of all is the length of time Imperial kept using Heisey's original mark. The 1958-to-1968 window comes from a single identification guide consulted for this piece. Heisey's own museum, Wikipedia's account of the company, and a 1973 National Depression Glass Association journal article on Imperial's reproductions all discuss the mark-versus-color identification problem without giving a specific year Imperial's marking practice changed. Until a second source turns up fixing that date, this guide treats 1968 as reported rather than established.

What one sells for now

A Chanticleer vase sold at Apple Tree Auction Center in Newark, Ohio — Heisey's own hometown — on June 13, 2013, for $15, against a pre-sale estimate of $20 to $2,000. The sale landed below even the low end of that estimate, and the estimate's own hundredfold spread is itself a kind of evidence: it says the house itself was not confident what a routine example of this particular shape was worth going in.

Current asking prices run higher and narrower. One seller currently lists a 6-inch clear Chanticleer vase at roughly $38 USD; another listing for a larger, 7.75-inch, 3-pound example carrying an impressed 1557 mark had already sold at an unlisted price by the time this guide was researched. Treat the $15 realized figure and the roughly $35–$55 asking range as two different kinds of number — one a confirmed sale, the other sellers' own current hopes — rather than averaging them into a single value.

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For a mark that turns out to be the forgery rather than a genuine later owner's own reuse of it, see the McCoy panther attribution guide. For another maker whose trademark history this project has traced through a federal filing, see the Vaseline glass trademark and patent guide. For the designer who shaped Heisey's animals also at work in ceramic, see Haeger's marks and model numbers. See more Field Guides