The company began production in about 1905, making eyedropper pens, although they may have been producing dip pens in the previous century. Some suggest that the output of the early company was of marginal quality, but if my very meagre exposure is anything to go by this is an overly harsh estimate; it’s not fantastic, but it’s well above “marginal”.
There was a change in ownership towards the end of the 1910s, apparently because the company’s owner had joined up to fight in the Great War and been killed. The new owners (apparently getting out of the liquor business in response to prohibition) changed the impression to New Diamond Point. Shortly thereafter, lever-filling pens were included in the lineup. The 1920s appear to have been the high point for this company in terms of absolute quality, as there was a gradual decline from the 1930s onwards; one wonders if the repeal of prohibition or the coming of the Great Depression had a greater role in this.
The company lasted into the 1950s, making pens with decent looking bodies and unremarkable points.
Models I’ve examined: