A very nice an unusual pair of mahogany wine coasters with brass stringing to the top edge. C1770. Similar one is illustrated in Robin Butlers Book Great British Wine Accessories 1550-1900, page 206
These coasters measure approx 15cm in diameter and should therefore be big enough for a magnum. They have a lovely dark, rich colour to them.
An Unusual Pair of 18th Century Brass & Mahogany Wine Coasters