Heisey mark (H in a diamond)

How to read it

A. H. Heisey & Co. opened its glass factory in Newark, Ohio, in April 1896 and made glass there until December 1957, when the factory closed for the Christmas holiday and did not reopen (National Heisey Glass Museum). It began with pressed glass made to look like cut glass and went on to fine crystal tableware (National Depression Glass Association). Augustus H. Heisey applied to register the trademark on 21 June 1901. The application described a plain Roman capital H enclosed in a diamond, the diamond’s long axis running the same way as the height of the letter, and said the mark had been in use since about 1 November 1900 (Joseph Lokay, Heisey News, 2003). It was pressed into the glass, on the inside of the bottom where possible; where it couldn’t be, a printed label carried it, usually in white on a blue ground.

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When the mark was registered

Lokay gives 6 August 1901 as the date the Patent Office registered the diamond H as trademark no. 36860; it was renewed in 1906 and again in 1931. An article by Lamar Birckbichler, reprinted by the National Depression Glass Association, gives 8 August 1901. Heisey also registered a plain diamond, without the H, in 1909.

Heisey without the H

Not every piece has the mark. Birckbichler points out that glass made between April 1896 and November 1900 predates it. From the 1920s many pieces were not marked, the mark grew smaller and moved to out-of-the-way places, some buyers asked for it to be ground off, and many items had only paper labels. Heisey Collectors of America adds that blown pieces had only the paper label, that wear on the moulds could blur the mark on pressed pieces, and that fire polishing could remove it. On stemware it is often at the top of the stem or hidden in the pressed design.

Who owns the Diamond H

After the factory closed, the Imperial Glass Corporation of Bellaire, Ohio, bought Heisey’s moulds and other assets in 1958, including the right to the Diamond H trademark, and made glass in some of the moulds until its bankruptcy in 1984. Heisey Collectors of America then acquired the moulds. HCA, founded in 1971, says it owns the rights to the Diamond H trademark along with the original moulds.

HCA’s own pieces

HCA has items made from the original moulds to raise funds. They are made in colours Heisey didn’t use and are marked HCA, with the year and a letter or symbol for the glass company that made them.

On bottles

The Society for Historical Archaeology’s researchers note that the Heisey Diamond H looks like the Diamond I that the Illinois Glass Co. used on bottles.