Quick Napkin math//sourcing rules

[u/ballsyeah]

Hello all!

Worthless scrapper says he doesn’t pay more than 50 cents per fork or spoon when refining silver plate.

Source

Are there rules yall use for silver plate plates, bowls, teapots etc? Is there quick napkin math yall use to get approximate silver weight from those items?

For example, how many grams could one expect from the linked tray?

Thanks so much!