Neat trick, except I think that glass is harder than the enamel on your teeth. You probably don't want to wear too much of that enamel off. Even if it weren't harder, at even the smallest size your body will never process that silica and it will certainly play hell with your intestine. You see, your intestine is very fragile and full of ucky poisonous goo. You don't want any holes in your intestine. Thirdly, be careful not to eat any crystal. Most crystal gets its distinctive qualities from the addition of lead. Lead is a bad thing to eat.