I never knew the powder check. Hey, out if curiosity, does the gold on your cheek test work?Did a quick look, and a butter knife in good condition listed for $50 - 100. This was the info listed: Mexican Silver 67 is a solid silver alloy consisting of over 60% silver and was made by The Holmes and Edwards Silver Company of Bridgeport, Conn. between 1882 and 1898 prior the International Silver Company taking them over. These pieces are highly resistant to tarnish and are hard to find. Appears you made quite a deal! Congrats. A quick test, if you have access is womens loose face powder/compact powder. This will work if you go to a garage sale or whatever and you want to do a quick test. Put the face powder on your inner forearm. Make a quick rub of the item. If a coin, or bullion, just turn on edge and drag across the powder quick, and it will leave a dark mark if it is silver. The purer the silver, the darker the line. Works for fair skin, like mine anyway. HH