I was informed that much of the GIA site went down at 5pm PST yesterday and will be down until Monday for scheduled maintenance. (I can’t login for my coursework because of it.) Not sure if it is impacting reports as well.
I can’t get it to reload today but I think the table was 66 percent, crown 40 degrees, pavilion 41.2 degrees. Lots of crystals in the center of the table, extra facet, some feathers and cavities on the edges, no clouds listed.
I can't see the cut pattern clearly in your photo (try and take a nice clear in focus top down photo of it) but you said you inherited the stone, with a table that big and a crown like that it could be a transitional stone. Do you know roughly how old the stone is? I'm asking because if it's a vintage or an Antique diamond that might also be another good reason not to mess with it.
if you want to sell it yourself try listing it on Loupetroop and get someone like Dave Atlas (lovely guy) to act as an intermediary for you, (which he would do for a nominal fee);