Had an elven or human caravan recently with studded gem for thade. Does that mean I can chain decorations by, say, studdyng gem, then encrusting some bone item with it, then decorating anything else with resulting bone ets.
Also I wonder if there's a way to build down. If i breach the cavern from above and start building downwards ramps or ladders to finally get down to it's floor shall I succeed?
I'm fairly sure you can only encrust finished goods with gems, bone, and other such things. You can't encrust just a stack of bones, it'd have to be a bone helm or something first. Similarly, I don't think you can decorate "cut gems" with anything, as they're only used in encrusting (or just trading away).
If you make a stockpile that only accepts large gems, leather, small cut gems and bone/ivory/horn/tooth far enough away from the other stockpiles, though, the craftsdwarf/jewelers who go to work at those workshops will encrust and decorate the large gems with aforementioned materials. It may be a smart idea to make a burrow and assign a couple of craftsdwarf to it, make a small food stockpile and a dining room next to it, because if your main dining room and your other stockpiles are (food and finished goods) are on the same level, sometimes they'll go have dinner and then grab, say, a rock mug from a stockpile in that level and run down/over to the workshop they're assigned to.
For extra value, only let craftsdwarves/jewelers of above a certain skill level work at these workshops.
Or you could make a lot of rock mugs. Whatever.