Seems like a "classic" Pu-eh bingcha nominally weighs 357 grams. Although China (PRC) went metric in 1987, I get the impression that 100,
400 and 500g cakes are a relatively recent phenomenon.
357g is presumably someone's interpretation of ten tael or Chinese ounces, now 50g but formerly about 37.5g. At the same time, in none of the superficial reading I've done has there been a tael of exactly
37.5g; the imperial treasury tael of 37.3g seems closest.
Anyone know the origin of the 357g "standard" bingcha? Or why 375g, a non-round number, is also common? I'm guessing that it's partly marketing (perhaps invoking archaic terminology, as age is respected in China), and partly the difficulty of specifying a precise weight when water content can easily vary by 10% or more. The baker's dozen was allegedly invented because short-weighting loaves could lead to shortening of limbs, so bakers gave a little extra as insurance.
Or does that weight or the number 357 have some other significance?
-DM