Get a big dwarf civilization, like, say, 6+ world tiles contained in their territory. Embark on a map with sand. Get magma and a magma glass furnace, start pumping out raw green glass, then have a gem cutter cut said raw glass and a gem setter set the cut glass onto stuff. Repeat until you've got a legendary+5 gem setter.
Sometime while you're accomplishing this, when the dwarven liaison comes by, order at least one of every form of gem available, including clear and crystal glass. Purchase at least one of every form of gem when the caravans show up again.
Make a piece of furniture that a room can be defined from, for instance a bed. Stockpile the piece of furniture, a bunch of food and drink, and all your cut gems in a place that has a bed, table, chair, jeweler's shop, and your legendary+5 gem setter. Seal that sector so no one may enter or leave (or use burrows to isolate your gem setter inside), then set your gem setter encrust that single piece of furniture with every single gem that exists.
That piece of furniture will now easily be worth 25,000 or more, well above what is needed to make a 1x1, wallless piece of dirt into a legendary room were that piece of furniture to be placed on it. No artifacts, quantum or otherwise, needed. No metal needed, either, though you could of course repeat this process with a legendary+5 metal crafter and every single metal in the game to get an even more overly-decorated object.