It has a 375 British 9ct gold hallmark on the first link which must be a later addition. It tests higher than 9ct more like 12ct.
Fitted with a later bolt ring closer. The item "Antique Victorian 58 inch long full length 9ct gold watch guard chain 25.9 grams" is in sale since Friday, May 12, 2017. This item is in the category "Jewellery & Watches\Vintage & Antique Jewellery\Vintage Fine Jewellery\Victorian (1837-1901)".The seller is "newtoyounotsecondhand" and is located in Glasgow, Glasgow (City of). This item can be shipped worldwide.