St Gauden's Double Eagle - Some Information

Dear all,

My mother passed away earlier this year and on looking through her things I found a 1927 St Gauden's double Eagle. I attach a photographs below (please excuse me I used an i-phone which I admit is not the best camera but what I had on me)

I am not a US Citizen and neither was my mother (actually we are/were both British). However my mother was raised in Belgium by foster parents when she was a small child during the second world war. I believe that her foster father was an industrialist (electronics) and my mother inherited the coin when her foster mother died

I don't know whether the coin was used as part of my foster grandfather's business or was something they bought as an investment. I don't even know what a $20 US gold coin was doing in Belgium

I would like to know a few things, What condition it is in (looks mint to me), whether I should encapsulate it and if so with whom.

Many thanks