I looked up the globe, and found that it is manufactured by the Alexander Kalifano company. The company site says that the body of the globe is opalite. I find that there is a man made substance called opalite. Given the price, I'd suppose it is the man made substance, and not the much I found a reference that says it is 2.5 on the Mohs scale, which makes it somewhat harder than plaster of paris, maybe as soft as copper. I can't find any info in if it is brittle.
Mineral opalite, a variety of true opal is very hard and brittle. The only examples I've found online show rather small stones, maybe 2" long. Again, this leads me to think the globe is the man made substance.
Good luck. My experience w. such things is negligible. Perhaps have the customer take it to a jewelry shop, or contact the Kalifano co. and see if they will offer advise.