Hi guys

So since I joined the forum I have started being able to take quite clear pics with my mediocre nikon coolpix and home made copystand. Mostly thanks to the regulars here like SuperDave.
Now I am having another prob that I just can not overcome(yet). Taking pics of slabbed coins. The camera always seems to want to focus on the light reflecting off the case and not focus on the coin itself. So I have been getting pics that are pretty clear, but not the super crisp sharp ones I get if they are not slabbed.
So how do you get around this when using a point and shoot? Please help :D