THE SMART TRICK OF CERIUM OXIDE THAT NO ONE IS DISCUSSING

Opal is tender and it lacks "toughness." Hardness may be the resistance to staying scratched, but toughness would be the resistance to breaking. If you do not fill your tumbler to capacity, your opal could possibly be tossed all over violently from the barrel.The toughness of alumina is usually enhanced by the addition of zirconia particles or sili