Andrew Nethercott Antiques has dated this piece to the 1910s.

The links are 5.3mm x 6.3mm x 3mm, the T bar is 39mm
9 .375 gold hallmarked.
Typical 9 carat golden colour, neither rose nor yellow.
In excellent condition with no apparent wear, sound, strong and ready to wear.
Total working length of chain 15" or 383mm, weight 35 grams
Andrew Nethercott Antiques has dated this piece to the 1910s.
Works of art, collectables, scientific and decorative antiques from the 17th - 20th century
You can view the stock and full dealer information on the Andrew Nethercott Antiques Profile Page