Quite honestly Roy I'd really need to send you a video for you to understand completely and I can't seem to get a three second one to fit on the share your stuff section but I guess the shape is a little out of true but it also has a window at certain angles that reveals a sand spot but after inspection with a light I seems to only go a very short distance into the bottom of the stone and could be easily removed without the stone losing any real weight besides on this stone it's not weight but pattern and uniformity of it's shape. I'll try to email you a video of it.
Are you just bringing the edges in a tad?
harlequin? luck duck