How should I package collectible banknote for shipping?

I believe we have some numismatists on the Dope.

While clearing out an elderly relatives stuff we came across some silver certificates in pristine condition. They look to be worth $6 or so each, based on eBay auctions. How should I package such a note so that it arrives in pristine/uncirculated condition? I searched the web and only found a method that would cost way more than the value of the notes.

Am I okay putting them in an envelope within a padded envelope? Or does anyone have suggestions as to what is usually done?

IANAN, but my first thought was in an envelope, between the pages of a hardcover book

When I did this years ago with a mis-cut, mis-printed $10 bill, I put in a plastic currency holder and sandwiched it between two sheets of sturdy cardboard which was cut to fit the envelope. It was sent USPS and I marked it “Do Not Fold”. It was received in perfect condition.

Thank you. “Currency holder” is the term I needed. I see I can buy those for 30 - 40 cents each. Just what I need for “free shipping.”

That is probably the best option for your case. Just note to whoever gets them that you have not provided for long-term storage, just for safe shipping. For longer-term you need specifically something PVC-free and/or archival in nature which could cost more than needed for what you are doing.

Absolute-last-ditch-to-save-costs ------- use a heavier plastic bag such as a ziplock as a holder and then sandwich that inside the two pieces of cardboard. Not the best by far but just from Point A to Point B it works fairly well.