A statement was read by the firm's sales manager, Claire Bradley
The closure of Tyrone Crystal's Dungannon factory is "a dreadful blow for the local area", Enterprise Minister Arlene Foster has said.
The company had been experiencing a downturn in demand for its products for some time, and 31 jobs will be lost.
It had been seeking a buyer in recent weeks, but there was no interest in acquiring it as a going concern.
Mrs Foster said it "is not just a manufacturer, it is an iconic brand that has attracted tourism interest".
She said she understood that efforts would continue to find a buyer for the business, either in whole or in part, and Invest NI would work with management "for as long as there remains any prospect of a sale".
In a statement Tyrone Crystal said: "The company and its management wish to take this opportunity to thank its loyal workforce for their valued contribution over the years and for their support during this difficult period."
Tyrone Crystal has traded for about 40 years, but changing tastes combined with the effects of the recession have been blamed for falling sales of its products.
Martin Mohan, who has worked for the company for 35 years, said it was the first time he had ever thought about the possibility of redundancy.
"It is just one of those things that has to sink in," he added.
"I think it has come to a head now where people have just said 'OK, well I think our final day is here'."
Local Sinn Fein MP Michelle Gildernew said it was "a difficult and uncertain time for the workers and their families".
"I spoke to some of the staff last night who are simply shell-shocked at the uncertainty of what is taking place," she said.
Meanwhile, a mining and construction firm has confirmed it is closing its County Tyrone factory at the end of the month.
Work carried out at Metso Minerals' plant in Cappagh, near Dungannon, will be transferred to its parent company's headquarters in Finland.
It decided last June that the factory would close. Since then, 29 out of its 50 employees have found new jobs.
Metso was formerly known as Masterscreen International. It was taken over by Metso in June 1999.
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