Different tugs would have had different size chains, dependent on the size of the original. As a guide, if one original link was 30 x 20 mm divide that by 24 and you have your answer.
In practice, what most of us do is look at the jewellery in a cheapo shop, and buy what looks correct for the chain.
Or, making your own from a piece of dowel and some soft brass wire is a doddle.
Chas.