I agree with apparently the majority, what the customer wants, the customer gets. I've done wedding / engagement rings with blue zircon, opal, tanzanite, labradorite and even elk's tooth. But I do have a frank discussion with them before work begins on the care and feeding of such fragile stones. I usually compare it to clothing and tell them that this piece will be like a fine silk blouse or a cashmere sweater as opposed to a Levi's jacket. You would never treat a cashmere sweater like you might denm or leather, never taking it off when weeding the garden or rock climbing and expect it to survive for fifty years so you could pass it on to your grandchildren. The same philosophy applies to fine jewelry, especially that which is created using fragile or delicate stones. Just like everything else you own, it will treat you the same way you treat it.
It is amazing to me how few people ever realize or had it explained to them that jewelry is just like anything else we own, it wears out with use. I can't tell you how many times I've heard "My grandmother wore this for fifty years, my Mom wore it for another thirty and it never had a lick of trouble until so-and-so cleaned it". Jewelry, unlike anything else, is expected to be absolutely bullet-proof. I blame it on sales people and others in the trade that don't seem to be at all concerned with the customer's long-term satisfaction with their product compared with their desire to close the sale.