Assay Office, City of London, 19 July 2013
Since 1300, English jewellers have been required to hallmark all precious metal products. We've just started making our first gold watch cases, so today I spent the afternoon at the London Assay Office registering the Hoptroff Hallmark.
The hallmark is five separate stamps. The first, the Sponsor's Mark, indicates the manufacturer. Our mark is the letters H and F in a shield.
The second stamp is the Fineness Mark. For our 18ct gold pieces, this is the number 750 in a rectangular octagon. For our occasional sterling silver pieces, it is the number 925 in an oval. Platinum parts will have a house-shaped stamp, but I'm not sure yet what the purity level will be, and thus what the number will be. With watch cases it's always a dilemma. You want a pure piece, but precious metals are soft, so copper and silver need to be mixed in for strength.
The third stamp is the Assay Office mark, which for London is a leopard's head. Curious, since it's been quite a few millennia since they roamed free here, but pretty all the same.
The fourth stamp is the Traditional Fineness Mark, which indicates the type of metal. Silver is a Lion Passant; Gold a crown; Platinum an orb.
The final stamp is the Date Letter Mark. Inside an octagon, there is an 'o' for 2013, a 'p' for 2014, and so on.
Look out for our hallmark on the underside of the watch strap lugs. We're waiting for our stamp to be made, so no photographs yet, but watch this space!