Even the untrained eye can discern the fakes' inferiority compared with watches built by British masters like Thomas Tompion, George Graham, and Thomas Mudge.
By Tompion's death, in 1713, daily variation was less than a minute, and by the late 19th century, marine chronometers were accurate to fractions of a second per day.
When Thomas Tompion began making watches around 1670, the best ones money could buy had only an hour hand--and a tendency to gain or lose some 10 minutes per day.