How should I store my expensive coins? In non-PVC flips with pertaining info in a safety deposit box!!
In a vacuum - reaction to the atmosphere will tarnish them horribly especially if heat, humidity, salt air. Flip them quickly or keep them in airtight container w silica gel.....or your portfolio may tank. During 60’s and 70’s had mine in sealed glass jar with silica gel then jar stored in safe. Then when slabbing came along they were as pristine as day went in safe and got high grades. Sold most by height of 88-89 market before crash then bought nice world gold coins near melt.
First of all, good advice above. I have most of my coins in non-PVC Safe-T-Flips and others in Marcus snap together holders. Bulk stuff like circulated Franklins in CoinSafe tubes. Also, there's some really spendy Ike dollars out there, so they should not be dismissed out of hand. Also as mentioned, keeping humidity low is a good idea, if at all possible.