Dating numbers blog
Using the serial number you can use the charts below to find the date when your machine was given a batch assignment at the factory.
For additional reference and a few more dates for those later year machines, however, we have included some of these dating records in the charts above, sourced from JJ & Leo's Featherweight 221 Factory site as well as uk's site.
The dates given below are the days on which those batches were started, together with the number of machines in each consignment.
The first Featherweights batched in 1933 begin with the two-letter prefix 'AD'.
Vintage jewelry from other countries may have European purity marks, such as “585” for 14K gold and “750” for 18K gold, as shown in the photo below.
Vintage costume jewelry usually doesn’t have purity marks, but will often have a maker’s mark (commonly called the signature), and can sometimes have a retailer mark and/or patent or inventory marks.
Prior to the change in the copyright law in 1955, the designs were patented.