The opals in pipes are synthetic Gilson opals. Real opals will crack.
OPALS-
Opal is one of the world’s most beautiful and precious gemstones, predominantly found in Australia. It is one of only six types of precious gemstones found on planet earth, sharing prestigious company with diamonds, rubies, sapphires, emeralds, and pearls. You can not use a natural opal in glass. You must use a created opal called a Gilson Opal. The term, “laboratory-grown” means that our products faithfully mirror Mother Nature’s opal. Gilson-Created™ Opals have virtually identical chemical, physical and optical properties as do their naturally-occurring counterparts. The exception is that our lab-grown products are harder and more durable than most of those from nature. We no longer produce Gilson Created opal varieties in rough, uncut volumes, loose stone assortments and in fine jewelry designs. So, if technology is your fascination, beauty and affordability your pursuit…have a look. Click here to learn more about natural opals. 
