Opal was formed many millions of years ago, when a combination of silica and water flowed into cracks and spaces in the ground. This then gradually hardened and solidified to become opal. Opals contain water, which makes them very sensitive to heat. They are soft and can be cracked or chipped easily. Opals should be stored in moist absorbent cotton.we have finest quality of blue opal rough stone, the price of the stone is 850 per kg. And the minimum order quantity is 10 kg. You will be pleased we guaranteed. Shipping charges will be extra.