During a recent opal cutting class we experimented by completely dry cutting these stones. We did 5 cabochons completely dry (using diamond paste on canvas for a polish) and 5 wet. Of the wet stones 3 of 5 cracked after wetting. All of the dry cut stones finished up with no cracks. In the next class the following month we tried to narrow this down a bit and only roughed (360 grit grinding through 600 grit sanding) the stones dry (frequently using a dry trim saw to cut bits and pieces off instead of using the grinder and avoiding clouds of dust). We did use water sparingly for the 1200 grit and 3000 grit sanding through polish steps with no cracking. Dry cutting is very dusty, but this limited experiment showed the effectiveness of dry cutting. I am now wondering if some of these stone have much amplified hydrophane properties which causes them to absorb more water than the stones silica structure can hold and thus crack. Please let me know how your stones turn out and if dry cutting works for you. Steve 406-651-4947 or firstname.lastname@example.org.
Tips from Neil in Queensland Australia: I found your website during a Google hunt on cutting tips for Welo. It’s the most helpful and descriptive source on the web in my opinion. I have been cutting the Welo opals dry ever since with huge success. In the last week, after grading, I have cut and pre-polished over 40 opals without cracking. The only cracks are from the ones missed after trimming and drying. I use your dopping method too, using exterior aquadhere which is a more durable pva woodworking glue. Clear nail polish is still needed.