Too much!
When in the opal mining regions, you do see cheap watches with opal dials in some of the shops. Very cheap quartz watches of course. I have thought about trying to use opal in some manner on a dial of a watch, but thickness is an issue. To use a stone set on the dial, you would need to make sure all the hands clear it - long posts on the movement and possibly clearance issues under the crystal as a result. To make a dial out of opal it would have to be cut so thin it would be super fragile. Not just to handle and assemble, but also for removing replacing hands for service. For example you have to be very careful removing hands from an MOP dial - slightest pressure on the dial and it will crack.
Click to expand...