Heisey never made black glass for commercial production. With the exception of one piece I know about, it has been found only in Newark, Ohio. Some pieces of it were given to friends of the management and some were sold at the Heisey outlet store after there was a massive cleanout of all stock in 1958. Everybody wants a piece of it in his or her collection, but it is not available. All known items of it are in the hands of Heisey collectors.
Heisey black glass has been found only in cobalt blue glass. Mr. Olson, the chemist at the time, made black glass from cobalt. This fact can be proven by holding a piece of Heisey black glass to the light. The cobalt in it is very pronounced. Shades of blue, varying from a very light blue to black can be made with cobalt by regulating the amount of cobalt added to the mix. The more cobalt added, the darker the color.
In a recent issue of Rainbow Review (May, 1974), there was a composition prepared by Jabe Tarter in which was shown a black vase, purportedly made by Heisey. Further, Heisey was listed with several other companies as a maker of black glass. The black glass vase shown is NOT a Heisey product. It is not a part of any of the many Heisey patterns. Also as stated above, Heisey made some black glass experimentally, but NOT commercially. Therefore it cannot be found on the market.
All of the black glass made experimentally by Heisey from cobalt was made under the close supervision of Mr. Emmett Olson, the chemist. His experiments were conducted during the 1930s. Nor did Heisey get into the black glass fad prior to this date.
Heisey was principally the maker of clear crystal glass, very little colored glass having been made. Although Heisey made glass in several colors, it was never made in large quantities, nor in quantities comparable to the colored glass made by its competitors. Mr. A. H. Heisey, the founder, and Thomas Clarence Heisey, the third president, were not colored glass enthusiasts.
It is thought that not over 400 or 500 pieces in all were made in the black cobalt color. Less than 50 are known to exist. When Heisey closed shop in December 1957, the warehouse was cleaned out of all glass in stock. During the clean out process, a box of black glass was found and taken to the outlet store where it was sold at 10¢ apiece. One man bought 6 of the No. 341 mayonnaise plates and stored them in his attic until recently, when he sold them for $30 each. Now the price is over $300 each.
When the small black glass melt was on the floor, Mr. Heisey had six 8" Lariat plates made, which he presented to a friend of his. Eventually, all six of the plates found their way into the hands of Heisey collectors.
All of the authentic black Heisey glass which I have seen is cobalt blue black. All of the other black glass which was made by other glass outfits has a dense purple or amethyst color when held to the light. All of which more or less proves that there is no pure black glass on the market.
Whether other companies made any cobalt blue black glass is not known. But you can be assured that any amethyst or purple black glass is NOT Heisey.