Large loose Pearl

Hello I’ve been looking at pearls as last night I stumbled across some online for some reason then decided to have a look through my collection to see if I could learn a bit about them by comparison, one of this first to catch my eye was this beauty, looks like one I saw described as natural and also had a mark on one side like it was attached to a shank maybe?? Not sure what else it could be, it’s big so I just weighed it & it’s 5.25 ct. it looks like maybe a south sea and I’m wondering if I should get it tested as it might be worth something . Hopefully a pearl fan will know more , I’ve noticed it is ice cold. Not sure if that’s good