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Hi.
It looks like a genuine Paul Ysart, and the colour tinge of the glass suggests to me it is 1930s - 1940s. (The colour is from the manganese in the glass mix, which is used to remove the natural green tinge from iron in the sand. If there is a little too much manganese in the mix, and especially if the weight is exposed to sunlight, then over time this tinge appears. It happens to some Bohemian weights too.)
Alan