Our NMR magnets have a variety of vintages. Believe it or believe it not – out 300 MHz solid-state NMR magnet is more than 40 years old! Older magnets are unshielded, they have a much larger stray field and you should be much more careful about bringing any ferromagnetic materials close to them. The size of a magnet is not an indication of its stray field.
So make it a habit: when working with an NMR instrument empty empty your pockets and do not bring the following close to the magnet: your wallet (credit cards and coins), keys, cellphones, watches, penknives etc. If any of these items comes too close they might be destroyed and/or sucked into the magnet, which can cause a very expensive damage and serious injuries might happen as well.
Pls also watch what you are wearing in your hair. Our instruments are named after star-wars characters but the princess amidala hairdo, which required a lot of hairpins, is not a good idea!
My experience with jewelry is that it is usually safe as far as it is made of stainless steel, gold or silver is ok; jewelry form the dollar store often is not. I had to tell one user to back off very slowly from the magnet because their otherwise dangling earrings were now pointing towards the magnet.
In case of doubt: we do have a very strong permanent magnet, which can be used to test jewelry, watches, etc. for their safety.
P.S. Wireless earbuds have become very popular. Those contain ferromagnetic components. So for everybody’s safety, pls do not wear them in the NMR lab.