Probably the best move you can make for a double eagle, if you are not interested in slabbing. None of my coins are slabbed.
Gold is soft and easily damaged, and especially so with a double eagle, where there is much more area to damage with an accidental knock.
When it is in a capsule, you can handle it just like an Ike.
My LCS has a range of British
Royal Mint screw shut capsules that came from British proof coins. They provide a very positive air tight seal. Some of these capsules even come with their own individual coin case.
I have rehoused a 1937 George V1 gold proof Two Pound coin this way, but that is
not the way they were originally sold.
There is usually a range of hard acrylic snap shut capsules of various sizes available from your local coin dealer, and I am sure that they can be ordered in, if they haven't got any. Have a friendly chat over the 'phone with your local coin dealer.
Also a good move for proof silver coins (U.S. and World), that aren't already protected.
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There is
another way to adequately protect your double eagle.
Cut a piece of clear acetate plastic recovered from a food container, big enough to staple the double eagle in it.
Then put the plastic enveloped coin in a 2x2,
That is what I have done with my St Gaudens. It then fits snugly into a coin album pocket, and will never accidently fall out. My album pages are all
non PVC Mylar or polypropylene. Small six pocket album pages that fit nicely in my rather small safe.