Seiler & Co, Basel Seal, Image by StuE, Found by Swarfy.
Found in Essex.
One side has BASEL with a straight raised line above and below across the centre with a raised circular outer border - probably continuous. The other side has the company name around the inside of a continuous raised circular border. SEI(L?)(E?)R & (in the centre) CO (at the bottom edge).
From Paul Cannon, "Seiler & Co was a major silk ribbon manufacturer in Basel, Switzerland. Their arCHeco archives show that this form of their name started in 1888."