While looking for something else, I came across this little tidbit about toothpaste: The abrasive used in commercial toothpaste, hydrated silica, is actually crushed opal.
I like opals. I think they are one of the loveliest gems around. I love the play of colors they have. See www.thaigem.com/dis_opal.php.
I like the idea of having crushed ones in my mouth.